Air-conditioning apparatus

ABSTRACT

To provide an air-conditioning apparatus that is safer and has small conveying power for such as water at the indoor unit side can be made small. It is characterized in that a compressor  10  and a heat source side heat exchanger  12  are accommodated in a heat source apparatus  1 , an intermediate heat exchanger  15  and a pump  21  in a relay unit  3 , a use side heat exchanger  26  in an indoor unit  2 , respectively, and when a controller  60  makes the compressor  10  stop based on the thermo-off due to decrease in the heat load in the use side heat exchanger  26  or an operation stop instruction, the controller  60  makes the pump  21  stop after the compressor  10  is stopped or almost at the same time as the stop.

TECHNICAL FIELD

The present invention relates to an air-conditioning apparatus used fora multiple-air conditioner for buildings for example.

BACKGROUND ART

Conventionally, there is a multi-air conditioner for buildings for whichan air-conditioning apparatus is applied in which, by making arefrigerant circulate between an outdoor unit, which is a heat sourceinstalled outdoors, and an indoor unit installed indoors, cooling energyor heating energy is transferred to an area to be air-conditioned suchas an inside of a room, and cooling operation or heating operation isadapted to be performed. As for the refrigerant employed by such theair-conditioning apparatus, for example, an HFC type refrigerant isoften used. In recent years, a natural refrigerant such ascarbon-dioxide (CO₂) has come to be used.

There is an air-conditioning apparatus having other configurationsrepresented by a chiller system. In such an air-conditioning apparatus,cooling energy or heating energy is generated in the heat sourceapparatus installed outdoors, the cooling energy or heating energy istransferred to a heat medium such as water and an antifreezing liquidthrough a heat exchanger installed in the indoor unit, and they aretransferred to such as a fan coil unit or a panel heater, which is anindoor unit installed in the area to be air-conditioned, to performcooling operation or heating operation. (For example, refer to PatentLiterature 1.)

CITATION LIST Patent Literature

-   Patent Literature 1 Japanese Patent No. 2006-3047 (page 4-5, FIG. 1)-   Patent Literature 2 Japanese Patent No. 2005-56722 (page 4-5, FIG.    6)

SUMMARY OF INVENTION Technical Problem

In the conventional air-conditioning apparatus, since a high-pressurerefrigerant is transferred into the indoor unit and utilized, when therefrigerant leaks indoors, users might be subjected to adverse effects.The chiller exchanges heat between the refrigerant and water outdoorsand transfers water into the indoor unit, so that conveying power ofwater is too large to be energy-saving disadvantageously.

The present invention is made to solve the above-mentioned problems andits purpose is to provide an air-conditioning apparatus that is saferand has small conveying power for such as water in the indoor unit side.

The air-conditioning apparatus according to the present invention has:

at least one unit of an intermediate heat exchanger that exchanges heatbetween a refrigerant undergoing two-phase change or a refrigerant undera supercritical condition and a heat medium which is different from therefrigerant such as water and antifreezing liquid;

a refrigeration cycle in which a compressor, an outdoor heat exchanger,at least one expansion valve, and a refrigerant side flow path of theintermediate heat exchanger are connected via piping through which therefrigerant flows;

a heat medium circulation circuit in which a heat medium side flow pathof the intermediate heat exchanger, a pump, and a use side heatexchanger are connected via piping through which the heat medium flows;and

a controller that controls drive of the compressor and the pump.

The compressor and the outdoor heat exchanger are accommodated in a heatsource apparatus.

The intermediate heat exchanger and the pump are accommodated in a relayunit.

The use side heat exchanger is accommodated in an indoor unit.

When the compressor is stopped based on the thermo-off due to decreasein the air-conditioning load in the use side heat exchanger or anoperation stop instruction, the controller makes the pump stop after oralmost at the same time of the stop of the compressor.

Advantageous Effects of Invention

According to the air-conditioning apparatus of the present invention,stable operation can be continued. It is possible to preventrefrigeration cycle operation efficiency from deteriorating such thatthe high-pressure of the refrigerant fluctuates and improve systemefficiency, surely achieving high energy-saving performance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1

FIG. 1 is a total configuration diagram showing an example of aninstallation condition of an air-conditioning apparatus according toEmbodiment 1.

FIG. 2

FIG. 2 is a total configuration diagram showing an example of aninstallation condition of an air-conditioning apparatus according toEmbodiment 1.

FIG. 3

FIG. 3 is a schematic circuit diagram of the configuration of theair-conditioning apparatus.

FIG. 4

FIG. 4 is a refrigerant circuit diagram showing a refrigerant flow atthe time of an cooling only operation mode of the air-conditioningapparatus.

FIG. 5

FIG. 5 is a refrigerant circuit diagram showing a refrigerant flow atthe time of an heating only operation mode of the air-conditioningapparatus.

FIG. 6

FIG. 6 is a refrigerant circuit diagram showing a refrigerant flow atthe time of a cooling-main operation mode of the air-conditioningapparatus.

FIG. 7

FIG. 7 is a refrigerant circuit diagram showing a refrigerant flow atthe time of a heating-main operation mode of the air-conditioningapparatus.

FIG. 8

FIG. 8 is a flowchart showing the processing flow at the time ofstopping each operation mode.

FIG. 9

FIG. 9 is a flowchart showing the processing flow at the time ofstarting each operation mode.

FIG. 10

FIG. 10 is a flowchart showing the processing flow at the time ofswitching from the cooling-main operation mode to the cooling onlyoperation mode.

FIG. 11

FIG. 11 is a flowchart showing the processing flow at the time ofswitching from the heating-main operation mode to the heating onlyoperation mode.

FIG. 12

FIG. 12 is a flowchart showing the processing flow at the time ofswitching from the cooling only operation mode to the cooling-mainoperation mode.

FIG. 13

FIG. 13 is a flowchart showing the processing flow at the time ofswitching from the heating only operation mode to the heating-mainoperation mode.

FIG. 14

FIG. 14 is a circuit diagram showing the circuit configuration of theair-conditioning apparatus according Embodiment 2.

FIG. 15

FIG. 15 is a flowchart showing the processing flow at the time ofstopping each operation mode.

FIG. 16

FIG. 16 is a flowchart showing the processing flow at the time ofstarting each operation mode.

FIG. 17

FIG. 17 is a flowchart showing the processing flow at the time ofswitching from the cooling-main operation mode to the cooling onlyoperation mode.

FIG. 18

FIG. 18 is a flowchart showing the processing flow at the time ofswitching from the heating-main operation mode to the heating onlyoperation mode.

FIG. 19

FIG. 19 is a flowchart showing the processing flow at the time ofswitching from the cooling only operation mode to the cooling-mainoperation mode.

FIG. 20

FIG. 20 is a flowchart showing the processing flow at the time ofswitching from the heating only operation mode to the heating-mainoperation mode.

REFERENCE SIGNS LIST

-   1 heat source apparatus (outdoor unit)-   2, 2 a, 2 b, 2 c, 2 d indoor unit-   3 relay unit-   3 a first relay unit-   3 b second relay unit-   4 refrigerant pipeline-   4 a first connection pipeline-   4 b second connection pipeline-   5, 5 a, 5 b pipeline-   6 outdoor space-   7 living space-   9 building-   10 compressor-   11 four-way valve-   12 heat source side heat exchanger-   13 a, 13 b, 13 c, 13 d check valve-   14 gas-liquid separator-   15 intermediate heat exchanger-   15 a first intermediate heat exchanger-   15 b second intermediate heat exchanger-   16 a, 16 b, 16 c, 16 d, 16 e expansion valve-   17 accumulator-   21 pump-   21 a first pump-   21 b second pump-   22, 22 a, 22 b, 22 c, 22 d flow path switching valve-   23, 23 a, 23 b, 23 c, 23 d flow path switching valve-   24, 24 a, 24 b, 24 c, 24 d stop valve-   25, 25 a, 25 b, 25 c, 25 d flow amount adjustment valve-   26, 26 a, 26 b, 26 c, 26 d use side heat exchanger-   27, 27 a, 27 b, 27 c, 27 d bypass-   31, 31 a, 31 b first temperature sensor-   32, 32 a, 32 b second temperature sensor-   33, 33 a, 33 b, 33 c, 33 d third temperature sensor-   34, 34 a, 34 b, 34 c, 34 d fourth temperature sensor-   35 fifth temperature sensor-   36 pressure sensor-   37 sixth temperature sensor-   38 seventh temperature sensor-   50 non-living space-   60 controller-   100 air-conditioning apparatus-   125, 125 a, 125 b, 125 c, 125 d flow amount adjustment valve-   200 air-conditioning apparatus

DESCRIPTION OF EMBODIMENTS Embodiment 1

Hereinafter, descriptions will be given to embodiments of the presentinvention.

Embodiment 1

FIGS. 1 and 2 are a total configuration diagram showing an example of aninstallation condition of an air-conditioning apparatus according toEmbodiment 1. Based on FIGS. 1 and 2, descriptions will be given to theconfiguration of the air-conditioning apparatus. The air-conditioningapparatus performs cooling operation or heating operation using arefrigeration cycle (a refrigeration cycle and a heat medium circulationcircuit) that circulates a refrigerant (a heat source side refrigerantand a heat medium (such as water and antifreezing liquid)). In somefollowing drawings including FIG. 1, the size of each component membermay be different from actual size.

As shown in FIG. 1, the air-conditioning apparatus has: one unit of aheat source apparatus 1, which is a heat source unit; two or more indoorunits 2; and a relay unit 3 that intervenes between the heat sourceapparatus 1 and the indoor unit 2. The relay unit 3 exchanges heatbetween a heat source refrigerant and a heat medium. The heat sourceapparatus 1 and the relay unit 3 are connected by a refrigerant pipeline4 that makes the heat source refrigerant flow through. The relay unit 3and the indoor unit 2 are connected by a pipeline 5 that makes the heatmedium flow through. Cooling energy or heating energy generated in theheat source apparatus 1 is adapted to be delivered into the indoor unit2. The numbers of connected units of the heat source apparatus 1, theindoor unit 2, and the relay unit 3 are not limited to those shown inthe figure.

The heat source apparatus 1 is usually disposed in an outdoor space 6,which is a space outside of the building 9 and the like and supplies theindoor unit 2 with cooling energy or heating energy via the relay unit3. The indoor unit 2 is disposed at a living space 7 such as a livingroom inside the building 9 into which the cooling air or heating air canbe transferred and server room and supplies the living space 7 to be anair-conditioning subject space with the cooling air or heating air. Therelay unit 3 is, as a separate body from the heat source apparatus 1 andindoor unit 2, configured to be disposed in a position (hereinafter,referred to as a non-living space 50) different from the outdoor space 6and living space 7, connects the heat source apparatus 1 and indoor unit2, and transfers cooling energy or heating energy supplied by the heatsource apparatus 1 to the indoor unit 2.

The outdoor space 6 is a place existing outside of the building 9,giving an impression of a rooftop shown in FIG. 1, for example. Thenon-living space 50 is a space different from the living apace 7,however inside the building 9, giving an impression of a place wherethere are not always people like on a hall way, under the roof of acommon zone, a common section including an elevator and the like, amachine room, a computer room, a warehouse or the like. The living apace7 is inside the building 9, giving an impression of a place where thereare always people or a place where there are a number of or few peopletemporarily, for example, an office, a class room, a conference room, adining, a server room or the like.

The heat source apparatus 1 and relay unit 3 are connected using tworefrigerant pipelines 4. The relay unit 3 and each indoor unit 2 areconnected by two pipelines 5 respectively. Thus, by connecting the heatsource apparatus 1 with the relay unit 3 by two refrigerant pipelines 4and by connecting the indoor unit 2 with the relay unit 3 by twopipelines 5, construction of the air-conditioning apparatus isfacilitated.

As shown in FIG. 2, the relay unit 3 may be configured by being dividedinto one first relay unit 3 a and two second relay units 3 b derivedfrom the first relay unit 3 a. Thus, two or more second relay units 3 bcan be connected with one first relay unit 3 a. In this configuration,there are three refrigerant pipelines 4 between the first relay unit 3 aand second relay units 3 b. Detailed descriptions will be given later todetails of the pipeline path.

In FIGS. 1 and 2, the indoor unit 2 is shown using a ceiling cassettetype as an example. However, it is not limited thereto, but it may beany type as long as cooling energy or heating energy can be blown offinto the living space 7 directly or via a duct. For example, aceiling-concealed type or a ceiling-suspended type is allowable.

In FIG. 1, although a case where the heat source apparatus 1 isinstalled in the outdoor space 6 is shown as an example, it is notlimited thereto. For example, the heat source apparatus 1 may beinstalled in a surrounded space such as a machine room with aventilating hole, may be installed inside a building 9 as long as heatcan be exhausted by an exhaust duct outside the building 9, or may beinstalled in the building 9 when employing a water-cooled type heatsource apparatus 1. Even if the heat source apparatus 1 is installed insuch places, no problem will occur in particular.

Further, the relay unit 3 may be installed in the vicinity of the heatsource apparatus 1. However, when the distance between the relay unit 3and the indoor unit 2 is too long, carrying power of the heat mediumbecomes considerably large, resulting in the reduction of power-savingeffect.

FIG. 3 is a schematic circuit diagram of the configuration of theair-conditioning apparatus 100. Based on FIG. 3, descriptions will begiven to a detailed configuration of the air-conditioning apparatus 100.As shown in FIG. 3, the heat source apparatus 1 and the relay unit 3 areconnected via the first intermediate heat exchanger 15 a and the secondintermediate heat exchanger 15 b that are provided with the second relayunit 3 b. They are connected with the relay unit 3 and indoor unit 2 aswell via the first intermediate heat exchanger 15 a and the secondintermediate heat exchanger 15 b that are provided with the second relayunit 3 b. In the following, descriptions will be given to theconfiguration and function of each constituent apparatus provided withthe air-conditioning apparatus 100. In the FIG. 3 and after, a case isshown where the relay unit 3 is divided into the first relay unit 3 aand the second relay unit 3 b.

Heat Source Apparatus 1

In the heat source apparatus 1, the compressor 10, the four-way valve11, the heat source side heat exchanger (outdoor heat exchanger) 12, andthe accumulator 17 are serially connected by the refrigerant pipeline 4and accommodated therein. In the heat source apparatus 1, there areprovided the first and second connection pipelines 4 a and 4 b and thestop valves 13 a, 13 b, 13 c, and 13 d. By providing the first andsecond connection pipelines 4 a and 4 b and the stop valves 13 a, 13 b,13 c, and 13 d, the heat source side refrigerant flow that is made toflow into the relay unit 3 can be directed to a certain directionregardless of the operation required by the indoor unit 2.

The compressor 10 absorbs and compresses the heat source siderefrigerant to turn it into a high-temperature high-pressure state, andmay be constituted by an inverter compressor or the like capableperforming capacity control. The four-way valve 11 switches the heatsource side refrigerant flow at the time of heating operation and theheat source side refrigerant flow at the time of cooling operation. Theheat source side heat exchanger 12 functions as an evaporator at thetime of heating operation, functions as an condenser at the time ofcooling operation, exchanges heat between the air supplied by a fan notshown, and the heat source side refrigerant, and turns the heat sourceside refrigerant into an vaporized gas or a condensed liquid. Theaccumulator 17 is provided at the suction side of the compressor 10 andstores an excess refrigerant.

The check valve 13 d is provided with the refrigerant pipeline 4 betweenthe relay unit 3 and the four-way valve 11 and allows the heat sourceside refrigerant to flow only in a predetermined direction (thedirection from the relay unit 3 to the heat source apparatus 1). Thecheck valve 13 a is provided with the refrigerant pipeline 4 between theheat source side heat exchanger 12 and the relay unit 3 and allows theheat source side refrigerant to flow only in a predetermined direction(the direction from the heat source apparatus 1 to the relay unit 3).The check valve 13 b is provided with the first connection pipeline 4 ato allow the heat source side refrigerant to flow in the direction fromthe upstream side of the check valve 13 d to the upstream side of thecheck valve 13 a. The check valve 13 c is provided with the secondconnection pipeline 4 b and allows the heat source side refrigerant toflow in the direction from the downstream side of the check valve 13 dto the downstream side of the check valve 13 a.

The first connection pipeline 4 a connects between the refrigerantpipeline 4 at the upstream side of the check valve 13 d and therefrigerant pipeline 4 at the upstream side of the check valve 13 a inthe heat source apparatus 1. The second connection pipeline 4 b connectsbetween the refrigerant pipeline 4 at the downstream side of the checkvalve 13 d and the refrigerant pipeline 4 at the downstream side of thecheck valve 13 a in the heat source apparatus 1. In FIG. 2, although acase where the first and second connection pipelines 4 a and 4 b and thecheck valves 13 a, 13 b, 13 c, and 13 d are provided as an example, itis not limited thereto and they may not necessarily be provided.

Indoor Unit 2

In the indoor units 2, use side heat exchangers 26 are mountedrespectively. The use side heat exchanger 26 is adapted to be connectedwith the stop valve 24 of the second relay unit 3 b and the flow amountadjustment valve 25 via the pipeline 5. The use side heat exchanger 26exchanges heat between the air supplied by the fan, not shown, and theheat medium and generates a heating air or a cooling air for supplyingit to the air-conditioning subject area.

In FIG. 3, a case is shown where four indoor units 2 are connected withthe second relay unit 3 b and they are illustrated as the indoor units 2a, 2 b, 2 c, and 2 d from under this sheet. Corresponded with the indoorunits 2 a, 2 b, 2 c, and 2 d, the use side heat exchangers 26 areillustrated as use side heat exchangers 26 a, 26 b, 26 c, and 26 d fromunder this sheet. Additionally, like FIG. 1, the connection number ofthe indoor unit 2 is not limited to four shown in FIG. 3.

Relay Unit 3

The relay unit 3 is constituted by dividing the housing into the firstrelay unit 3 a and second relay unit 3 b. Thereby, as mentioned above,one first relay unit 3 a can be connected two or more second relay units3 b. In the first relay unit 3 a, a gas-liquid separator 14 and anexpansion valve 16 e are provided. In the second relay unit 3 b, thereare provided two intermediate heat exchangers 15, four expansion valves16, two pumps 21, four flow path switching valves 22, four flow pathswitching valves 23, four stop valves 24, and four flow amountadjustment valves 25.

The gas-liquid separator 14 is connected with one refrigerant pipeline 4connecting the heat source apparatus 1 and two refrigerant pipelines 4connecting the first intermediate heat exchanger 15 a and the secondintermediate heat exchanger 15 b of the second relay unit 3 b anddivides the heat source side refrigerant supplied by the heat sourceapparatus 1 into a vapor refrigerant and a liquid refrigerant. Theexpansion valve 16 e is provided between the refrigerant pipeline 4connecting the expansion valves 16 a and 16 b and the gas-liquidseparator 14 and functions as a decompression valve and a throttleapparatus to decompress and expand the heat source side refrigerant. Theexpansion valve 16 e may be constituted by such as an electronicexpansion valve whose opening-degree can be controlled variably.

Two intermediate heat exchangers 15 (the first and the secondintermediate heat exchangers 15 a and 15 b) function as a condenser oran evaporator, exchanges heat between the heat source side refrigerantand the heat medium to supply cooling energy or heating energy generatedin the heat source apparatus 1 to the indoor unit 2. In order to flowthe heat source side refrigerant, the first intermediate heat exchangers15 a is provided between the gas-liquid separator 14 and the expansionvalve 16 d to help the heat medium heat. In order to flow the heatsource side refrigerant, the second intermediate heat exchangers 15 b isprovided between the expansion valve 16 a and the expansion valve 16 cto help the heat medium cool.

The four expansion valves 16 (expansion valves 16 a to 16 d) function asa decompression valve and a throttle apparatus to decompress and expandthe heat source side refrigerant. The expansion valve 16 a is providedbetween the expansion valve 16 b and the second intermediate heatexchanger 15 b. The expansion valve 16 b is provided so as to runparallel to the expansion valve 16 a. The expansion valve 16 c isprovided between the second intermediate heat exchanger 15 b and thefirst relay unit 3 a. The expansion valve 16 d is provided between thefirst intermediate heat exchanger 15 a and the expansion valves 16 a and16 b. The four expansion valves 16 may be constituted by such as anelectronic expansion valve whose opening-degree can be controlledvariably.

The two pumps 21 (the first pump 21 a and the second pump 21 b) make theheat medium that flows through the pipeline 5 circulate. The first pump21 a is provided in the pipeline 5 between the first intermediate heatexchanger 15 a and the flow path switching valve 22. The second pump 21b is provided in the pipeline 5 between the second intermediate heatexchanger 15 b and the flow path switching valve 22. The kind of thefirst and the second pumps 21 a and 21 b are not limited in particular.They may be constituted by such as a pump capable of controllingcapacity.

The four flow path switching valves 22 (the flow path switching valves22 a to 22 d) are constituted by a three-way valve to switch the heatmedium flow path. The number of the flow path switching valve 22 isadapted to correspond to the number of installed indoor units 2 (it isfour, here). In the flow path switching valve 22, each of the threevalves is connected with the first intermediate heat exchanger 15 a, thesecond intermediate heat exchanger 15 b, and the stop valve 24,respectively, and being provided at the inlet side of the heat mediumflow path in the use side heat exchanger 26. In order to make themcorresponded with the indoor unit 2, the flow path switching valves 22a, 22 b, 22 c, and 22 d are illustrated from the downside of this sheet.

The four flow path switching valves 23 (the flow path switching valves23 a to 23 d) are constituted by a three-way valve to switch the heatmedium flow path. The number of the flow path switching valve 23 isadapted to correspond to the number of installed indoor units 2 (it isfour, here). In the flow path switching valve 23, each of the threevalves is connected with the first intermediate heat exchanger 15 a, thesecond intermediate heat exchanger 15 b, and the flow amount adjustmentvalve 25, respectively, and being provided at the outlet side of theheat medium flow path in the use side heat exchanger 26. In order tomake them correspond with the indoor unit 2, the flow path switchingvalves 23 a, 23 b, 23 c, and 23 d are illustrated from the downside ofthis sheet.

The four stop valves (the stop valves 24 a to 24 d) are constituted by atwo-way valve to open/close the pipeline 5. The number of the stop valve24 is adapted to correspond to the number of installed indoor units 2(it is four, here). The stop valve 24 is connected with the use sideheat exchanger 26 on one side and with the flow path switching valve 22on the other side respectively, and provided at the inlet side of theheat medium flow path of the use side heat exchanger 26. In order tomake them correspond with the indoor unit 2, the stop valves 24 a, 24 b,24 c, and 24 d are illustrated from the downside of this sheet.

The four flow amount adjustment valves 25 (the flow amount adjustmentvalves 25 a to 25 d) are constituted by a three-way valve to switch theheat medium flow path. The number of the flow amount adjustment valve 25is adapted to correspond to the number of installed indoor units 2 (itis four, here). In the flow amount adjustment valve 25, each of thethree valves is connected with the use side heat exchanger 26, thebypass 27, and the flow path switching valve 23, respectively, and beingprovided at the outlet side of the heat medium flow path in the use sideheat exchanger 26. In order to make them correspond with the indoor unit2, the flow amount adjustment valves 22 a, 22 b, 22 c, and 22 d areillustrated from the downside of this sheet.

The bypass 27 is provided so as to connect the pipeline 5 between thestop valve 24 and the use side heat exchanger 26 to the flow amountadjustment valve 25. The number of the bypass 27 is adapted tocorrespond to the number of installed indoor units 2 (it is four here,that is, bypasses 27 a, 27 b, 27 c, and 27 d). In order to make themcorrespond with the indoor unit 2, the bypasses 27 a, 27 b, 27 c, and 27d are illustrated from the downside of this sheet.

In the second relay unit 3 b, there are provided two first temperaturesensors 31, two second temperature sensors 32, four third temperaturesensors 34, four fourth temperature sensors, a fifth temperature sensor35, a pressure sensor 36, a sixth temperature sensor 37, and a seventhtemperature sensor 38. Information detected by these detection means issent to the controller (controller 60) that controls the operation ofthe air-conditioning apparatus 100 to be utilized for the control of thedrive frequency of the pump 21, the switching of the heat medium flowpath flowing through the pipeline 5 and the like.

The two first temperature sensors 31 (the first temperature sensors 31 aand 31 b) detect the temperature of the heat medium flowed out from theintermediate heat exchanger 15, that is, the temperature of the heatmedium at the outlet of the intermediate heat exchanger 15 and may beconstituted by a thermistor and the like, for example. The firsttemperature sensor 31 a is provided in the pipeline 5 at the inlet sideof the first pump 21 a. The first temperature sensor 31 b is provided inthe pipeline 5 at the inlet side of the second pump 21 b.

The two second temperature sensors 32 (the second temperature sensors 32a and 32 b) detect the temperature of the heat medium flowed into theintermediate heat exchanger 15, that is, the temperature of the heatmedium at the inlet of the intermediate heat exchanger 15 and may beconstituted by a thermistor and the like, for example. The secondtemperature sensor 32 a is provided in the pipeline 5 at the inlet sideof the intermediate heat exchanger 15 a. The second temperature sensor32 b is provided in the pipeline 5 at the inlet side of the secondintermediate heat exchanger 15 b.

The four third temperature sensors 33 (the third temperature sensors 33a to 33 d) are provided at the inlet side of the heat medium flow pathof the use side heat exchanger 26 to detect the temperature of the heatmedium flowing into the use side heat exchanger 26 and may beconstituted by a thermistor and the like. The number of the thirdtemperature sensors 33 is adapted to correspond to the number ofinstalled indoor units 2 (it is four, here). In order to make themcorrespond with the indoor unit 2, the third temperature sensors 33 a,33 b, 33 c, and 33 d are illustrated from the downside of this sheet.

The four fourth temperature sensors 34 (the fourth temperature sensors34 a to 34 d) are provided at the outlet side of the heat medium flowpath of the use side heat exchanger 26 to detect the temperature of theheat medium flowing out from the use side heat exchanger 26 and may beconstituted by a thermistor and the like. The number of the fourthtemperature sensors 34 is adapted to correspond to the number ofinstalled indoor units 2 (it is four, here). In order to make thecorresponded with the indoor unit 2, the fourth temperature sensors 34a, 34 b, 34 c, and 34 d are illustrated from the downside of this sheet.

The fifth temperature sensor 35 is provided at the outlet side of theheat source side refrigerant flow path of the first intermediate heatexchanger 15 a to detect the temperature of the heat source siderefrigerant flowing out from the first intermediate heat exchanger 15 aand may be constituted by a thermistor and the like. The pressure sensor36 is provided at the outlet side of the heat source side refrigerantflow path of the first intermediate heat exchanger 15 a to detect thepressure of the heat source side refrigerant flowing out from the firstintermediate heat exchanger 15 a and may be constituted by a pressuresensor and the like.

The sixth temperature sensor 37 is provided at the inlet side of theheat source side refrigerant flow path of the second intermediate heatexchanger 15 b to detect the temperature of the heat source siderefrigerant flowing into the second intermediate heat exchanger 15 b andmay be constituted by a thermistor and the like. The seventh temperaturesensor 38 is provided at the outlet side of the heat source siderefrigerant flow path of the second intermediate heat exchanger 15 b todetect the temperature of the heat source side refrigerant flowing outfrom the second intermediate heat exchanger 15 b and may be constitutedby a thermistor and the like.

The pipeline 5 that makes the heat medium flow through is constituted bythe pipeline connected with the first intermediate heat exchanger 15 a(hereinafter, referred to as pipeline 5 a) and the pipeline connectedwith the second intermediate heat exchanger 15 b (hereinafter, referredto as pipeline 5 b). The pipelines 5 a and 5 b are branched according tothe number of the indoor units 2 connected with the relay unit 3 (here,4 branches each). The pipelines 5 a and 5 b are connected by the flowpath switching valve 22, the flow path switching valve 23, and the flowamount adjustment valve 25. By controlling the flow path switching valve22 and the flow path switching valve 23, it is adapted to be determinedwhether the heat medium throwing through the pipeline 5 a is made toflow into the use side heat exchanger 26 or the heat medium flowingthrough the pipeline 5 b is made to flow into the use side heatexchanger 26.

In the air-conditioning apparatus 100, a controller 60 is provided thatcontrols the operation of each apparatus mounted in the heat sourceapparatus 1, the relay unit 3, and the indoor unit 2 based oninformation from a remote controller for receiving instructions fromeach detection means and users. The controller 60 is adapted to controlthe driving frequency of the compressor 10 mounted on the heat sourceapparatus 1, the rotation speed (including ON/OFF) of a fan installed inthe vicinity of the heat source side heat exchanger 12, switching of thefour-way valve 11 or the like, and to execute each operation mode to bementioned later. Further, the controller 60 is adapted to control therotation speed (including ON/OFF) of a fan installed in the vicinity ofthe use side heat exchanger 26.

Moreover, the controller 60 is adapted to control the drive of the pump21 mounted on the relay unit 3, the opening-degree of the expansionvalves 16 a to 16 d, switching of the flow path switching valve 22 andflow path switching valve 23, the opening and closing of the stop valve24, and switching of the flow amount adjustment valve 25. That is, thecontroller 60 has a function as flow amount control means that adjuststhe heat medium flow amount in the relay unit 3, flow path decisionmeans that decides the flow path of the heat medium, ON/OFF controlmeans that executes ON/OFF of each apparatus, and control target valuechange means that appropriately changes the set target value based oninformation from each detection means. The controller may be provided ineach unit. In that case, each controller may be set to be communicablewith each other. The control unit is constituted by a micro processorand the like.

In the air-conditioning apparatus 100, a refrigeration cycle isconstituted by connecting the refrigerant flow path of the compressor10, four-way valve 11, heat source side heat exchanger 12, and firstintermediate heat exchanger 15 a, the refrigerant flow path of thesecond intermediate heat exchanger 15 b, and the accumulator 17 by therefrigerant pipeline 4 through which the refrigerant circulates. Theheat medium circulation circuit is constituted by connecting the heatmedium flow path of the first intermediate heat exchanger 15 a, firstpump 21 a, and use side heat exchanger 26 in order by the pipeline 5 athrough which the heat medium is made to circulate. In the same way, theheat medium circulation circuit is constituted by connecting the heatmedium flow path of the second intermediate heat exchanger 15 b, secondpump 21 b, and use side heat exchanger 26 in order by the pipeline 5 bthrough which the heat medium is made to circulate. That is, eachintermediate heat exchanger 15 is connected with two or more use sideheat exchangers 26 in parallel and the heat medium circulation circuitis made to have two or more systems.

That is, in the air-conditioning apparatus 100, the heat sourceapparatus 1 and the relay unit 3 are connected via the firstintermediate heat exchanger 15 a and the second intermediate heatexchanger 15 b provided in the relay unit 3, and the relay unit 3 andthe indoor unit 2 are connected by the first intermediate heat exchanger15 a and the second intermediate heat exchanger 15 b. In the firstintermediate heat exchanger 15 a and the second intermediate heatexchanger 15 b, the heat source side refrigerant that is a primary sideheat medium circulating in the refrigeration cycle and the heat mediumthat is a secondary side refrigerant circulating the heat mediumcirculation circuit are adapted to exchanges heat.

Now, descriptions will be given to kinds of the refrigerant used in therefrigeration cycle and the heat medium circulation circuit. In therefrigeration cycle, non-azeotropic mixture refrigerant such as R407C,pseudo-azeotropic mixture refrigerant such as R410A and R404A, or singlerefrigerant such as R22 and R134a can be used. A natural refrigerantsuch as carbon dioxide and hydrocarbon can be used as well. By using thenatural refrigerant as the heat source side refrigerant, an effect isavailable to suppress greenhouse effect of the earth due to refrigerantleakage. In particular, since carbon dioxide performs heat exchange withno condensation at the high-pressure side under a supercriticalcondition, when the heat source side refrigerant and the heat medium ismade to be a counter flow form in the first intermediate heat exchanger15 a second intermediate heat exchanger 15 b as shown in FIG. 2, heatexchange performance can be improved at the time of heating or coolingthe heat medium.

The heat medium circulation circuit is connected with the use side heatexchanger 26 of the indoor unit 2 as mentioned above. Accordingly, ahigh-security heat medium is assumed to be used in the air-conditioningapparatus 100, considering a case where the heat medium leaks into theroom where the indoor unit 2 is installed. Therefore, water, anantifreezing liquid, and a water-antifreezing-liquid-mixture or the likecan be used for the heat medium. According to this configuration, evenif the refrigerant leaks from the pipeline, the leaked refrigerant canbe prevented from entering indoors, enabling to achieve highreliability. When the indoor unit 2 is installed at a place hating watersuch as a computer room, highly thermally insulative fluorinated inertfluid may be used as the heat medium.

Here, descriptions will be given to each operation mode that theair-conditioning apparatus 100 executes.

The air-conditioning apparatus 100 can perform cooling operation orheating operation in the indoor unit 2 based on instructions from eachindoor unit 2 itself. That is, in the air-conditioning apparatus 100,not only all the indoor units 2 can perform the same operation, but alsoeach indoor unit 2 can perform different operation respectively. In thefollowing, four operation modes that the air-conditioning apparatus 100performs will be explained along with the refrigerant flow: cooling onlyoperation mode in which all indoor units 2 in operation perform coolingoperation; heating only operation in which all indoor units 2 inoperation perform heating operation; cooling-main operation in which thecooling load dominates; and heating-main operation in which the heatingload dominates.

Cooling Only Operation Mode

FIG. 4 is a refrigerant circuit diagram showing a refrigerant flow inthe cooling only operation mode of the air-conditioning apparatus. InFIG. 4, cooling only operation mode will be explained by an example inwhich cooling load is generated only in the use side heat exchangers 26a and 26 b. That is, in FIG. 4 shows a case in which no cooling load isgenerated in the use side heat exchangers 26 c and 26 d. In FIG. 4, thepipeline denoted by a thick line shows the pipeline through which therefrigerant (heat source side refrigerant and heat medium) circulates. Aheat source side refrigerant flow direction is denoted by a solid linearrow and a heat medium flow direction by a dotted line arrow,respectively.

In the case of cooling only operation mode shown in FIG. 4, in the heatsource apparatus 1, the four-way valve 11 is switched so as to make theheat source side refrigerant discharged from the compressor 10 flow intothe heat source side heat exchanger 12. In the relay unit 3, the firstpump 21 a is stopped, the second pump 21 b is driven, the stop valves 24a and 24 b are made open, the stop valves 24 c and 24 d are closed, andthe heat medium is made to circulate between the second intermediateheat exchanger 15 b and each use side heat exchanger 26 (the use sideheat exchangers 26 a and 26 b). Under these conditions, the compressor10 starts operation.

Firstly, the heat source side refrigerant flow in the refrigerationcycle will be explained.

A low-temperature low-pressure refrigerant is compressed by thecompressor 10 and turned into a high-temperature high-pressure gasrefrigerant to be discharged. The high-temperature high-pressure gasrefrigerant discharged from the compressor 10 passes through thefour-way valve 11 to flow into the heat source side heat exchanger 12.Then, it is condensed and liquefied while releasing heat into the openair in the heat source side heat exchanger 12 to turn into ahigh-pressure liquid refrigerant. The high-pressure liquid refrigerantflowed out from the heat source side heat exchanger 12 passes throughthe check valve 13 a, flows out of the heat source apparatus 1, passesthrough the refrigerant pipeline 4 to flow into the first relay unit 3a. The high-pressure liquid refrigerant flowed into the first relay unit3 a flows into the second relay unit 3 b via the expansion valve 16 eafter flowing into the gas-liquid separator 14.

The refrigerant flowing into the second relay unit 3 b is throttled bythe expansion valve 16 a and expanded to turn into a low-temperaturelow-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phaserefrigerant flows into the second intermediate heat exchanger 15 b thatacts as an evaporator to turn into a low-temperature low-pressure gasrefrigerant while cooling the heat medium by absorbing heat from theheat medium circulating in the heat medium circulation circuit. The gasrefrigerant flowing out from the second intermediate heat exchanger 15 bflows out from the second relay unit 3 b and the first relay unit 3 aafter passing through the expansion valve 16 c to flow into the heatsource apparatus 1 via the refrigerant pipeline 4. The refrigerant thatflowed into the heat source apparatus 1 flows through the check valve 13d to be sucked again into the compressor 10 via the four-way valve 11and the accumulator 17. The expansion valves 16 b and 16 d are adaptedto have a small opening-degree such that no refrigerant flows and theexpansion valve 16 c is made to be full-open so as not to occur pressureloss.

Next, heat medium flow in the heat medium circulation circuit will beexplained.

In the cooling only operation mode, since the first pump 21 a isstopped, the heat medium circulates via the pipeline 5 b. The heatmedium cooled by the heat source side refrigerant in the secondintermediate heat exchanger 15 b flows in the pipeline 5 b by the secondpump 21 b. The heat medium having pressurized in and flowed out from thesecond pump 21 b passes through the stop valve 24 (stop valves 24 a and24 b) via the flow path switching valve 22 (flow path switching valves22 a and 22 b) to flow into the use side heat exchanger 26 (use sideheat exchangers 26 a and 26 b). Then, the heat medium absorbs heat fromthe indoor air in the use side heat exchanger 26 to perform cooling ofthe air-conditioning subject area such as an inside of a room where theindoor unit 2 is installed.

Thereafter, the heat medium flowed out from the use side heat exchanger26 flows into the flow amount adjustment valve 25 (flow amountadjustment valves 25 a and 25 b). Thereby, through the operation of theflow amount adjustment valve 25, only the heat medium necessary to coverthe air-conditioning load required in the air-conditioning subject areasuch as an inside of a room flows into the use side heat exchanger 26and the remaining heat medium flows through the bypass 27 (bypasses 27 aand 27 b) so as to bypass the use side heat exchanger 26.

The heat medium passing through the bypass 27 does not contribute toheat exchange, merges with the heat medium that has passed through theuse side heat exchanger 26, passes through the flow path switching valve23 (flow path switching valves 23 a and 23 b), and flows into the secondintermediate heat exchanger 15 b to be sucked into the second pump 21 bagain. The air-conditioning load required by the air-conditioningsubject area such as an inside of a room can be covered by controllingthe temperature difference between the third temperature sensor 33 andthe fourth temperature sensor 34 to keep a target value.

Thereby, since there is no need to flow the heat medium to the use sideheat exchanger 26 (including thermo-off) having no air-conditioningload, the flow path is closed by the stop valve 24 and the heat mediumis prevented from flowing into the use side heat exchanger 26. In FIG.4, while the heat medium is made to flow because in the use side heatexchangers 26 a and 26 b there is the air-conditioning load, there is noair-conditioning load in the use side heat exchangers 26 c and 26 d andthe corresponding stop valves 24 c and 24 d are made to be a closedstate. When a cooling load is generated from the use side heatexchangers 26 c or 26 d, the stop valve 24 c or 24 d may be opened andthe heat medium is made to circulate.

Heating Only Operation Mode

FIG. 5 is a refrigerant circuit diagram showing a refrigerant flow atthe time of the heating only operation mode of the air-conditioningapparatus 100. In FIG. 5, heating only operation mode will be explainedby a case where a heating load is generated only in the use side heatexchangers 26 a and 26 b as an example. That is, FIG. 5 shows a casewhere no heating load is generated in the use side heat exchangers 26 cand 26 d. In FIG. 5, the pipeline denoted by a thick line shows thepipeline through which the refrigerant (heat source side refrigerant andheat medium) circulates. A heat source side refrigerant flow directionis denoted by a solid line arrow and a heat medium flow direction by adotted line arrow, respectively.

In the case of the heating only operation mode shown in FIG. 5, in theheat source apparatus 1, the four-way valve 11 is switched so as to makethe heat source side refrigerant discharged from the compressor 10 flowinto the relay unit 3 without via the heat source side heat exchanger12. In the relay unit 3, the first pump 21 a is driven, the second pump21 b is stopped, the stop valves 24 a and 24 b are made open, the stopvalves 24 c and 24 d are closed so as to make the heat medium circulatebetween the first intermediate heat exchanger 15 a and each use sideheat exchanger 26 (the use side heat exchangers 26 a and 26 b). Underthese conditions, the compressor 10 starts operation.

Firstly, the heat source side refrigerant flow in the refrigerationcycle will be explained.

A low-temperature low-pressure refrigerant is compressed by thecompressor 10 and turned into a high-temperature high-pressure gasrefrigerant to be discharged. The high-temperature high-pressure gasrefrigerant discharged from the compressor 10 passes through thefour-way valve 11, flows through the first connection pipeline 4 a,passes through the check valve 13 b to flow out from the heat sourceapparatus 1. The high-temperature high-pressure gas refrigerant flowedout from the heat source apparatus 1 passes through the refrigerantpipeline 4 to flow into the first relay unit 3 a. The high-temperaturehigh-pressure gas refrigerant flowed into the first relay unit 3 a flowsinto the first intermediate heat exchanger 15 a after flowing into thegas-liquid separator 14. The high-temperature high-pressure gasrefrigerant flowed into the first intermediate heat exchanger 15 a iscondensed and liquefied to turn into a high-pressure liquid refrigerantwhile releasing heat to the heat medium circulating in the heat mediumcirculation circuit.

The liquid refrigerant flowing out from the first intermediate heatexchanger 15 a is throttled by the expansion valve 16 d and expanded toturn into a low-temperature low-pressure gas-liquid two-phase state. Thegas-liquid two-phase state refrigerant throttled by the expansion valve16 d passes through the expansion valve 16 b and flows through therefrigerant pipeline 4 to flow into the heat source apparatus 1 again.The refrigerant flowed into the heat source apparatus 1 passes throughthe second connection pipeline 4 b via the check valve 13 d to flow intothe heat source side heat exchanger 12 that operates as an evaporator.Then, the refrigerant flowed into the heat source side heat exchanger 12absorbs heat from the open air therein to turn into a low-temperaturelow-pressure gas refrigerant. The low-temperature low-pressure gasrefrigerant flowed out from the heat source side heat exchanger 12returns to the compressor 10 via the four-way valve 11 and theaccumulator 17. The expansion valves 16 a, 16 c, and 16 d are made tohave a small opening-degree such that no refrigerant flows.

Next, descriptions will be given to the heat medium flow in the heatmedium circulation circuit.

In the heating only operation mode, since the second pump 21 b isstopped, the heat medium circulates via the pipeline 5 a. The heatmedium heated by the heat source side refrigerant in the firstintermediate heat exchanger 15 a flows in the pipeline 5 a by the firstpump 21 a. The heat medium that is pressurized by the first pump 21 aand flowed out passes through the stop valve 24 (stop valves 24 a and 24b) via the flow path switching valve 22 (flow path switching valves 22 aand 22 b) to flow into the use side heat exchanger 26 (use side heatexchangers 26 a and 26 b). Then, the heat medium releases heat to theindoor air in the use side heat exchanger 26 to perform heating of theair-conditioning subject area of the inside of a room and the like wherethe indoor unit 2 is installed.

Thereafter, the heat medium flowed out from the use side heat exchanger26 flows into the flow amount adjustment valve 25 (flow amountadjustment valves 25 a and 25 b). Then, through the operation of theflow amount adjustment valve 25, only the heat medium necessary to coverthe air-conditioning load required in the air-conditioning subject areasuch as an inside of a room flows into the use side heat exchanger 26and the remaining heat medium flows through the bypass 27 (bypasses 27 aand 27 b) so as to bypass the use side heat exchanger 26.

The heat medium passing through the bypass 27 does not contribute toheat exchange, merges with the heat medium that has passed via the useside heat exchanger 26, passes through the flow path switching valve 23(flow path switching valves 23 a and 23 b), and flows into the firstintermediate heat exchanger 15 a to be sucked into the first pump 21 aagain. The air-conditioning load required in the air-conditioningsubject area such as an inside of a room can be covered by controllingthe temperature difference between the third temperature sensor 33 andthe fourth temperature sensor 34 to keep a target value.

Thereby, since there is no need to flow the heat medium to the use sideheat exchanger 26 (including thermo-off) having no air-conditioningload, the flow path is closed by the stop valve 24 and the heat mediumis prevented from flowing into the use side heat exchanger 26. In FIG.5, while the heat medium is made to flow because in the use side heatexchangers 26 a and 26 b there is the air-conditioning load, there is noair-conditioning load in the use side heat exchangers 26 c and 26 d andthe corresponding stop valves 24 c and 24 d are made to be a closedstate. When a cooling load is generated from the use side heat exchanger26 c or 26 d, the stop valve 24 c or 24 d may be opened and the heatmedium is made to circulate.

Cooling-Main Operation Mode

FIG. 6 is a refrigerant circuit diagram showing a refrigerant flow atthe time of the cooling-main operation mode of the air-conditioningapparatus 100. In FIG. 6, the cooling-main operation mode will beexplained by a case where a heating load is generated in the use sideheat exchangers 26 a and a cooling load is generated in the use sideheat exchangers 26 b, as an example. That is, FIG. 6 illustrates a casewhere neither heating load nor cooling load is generated in the use sideheat exchangers 26 c and 26 d. In FIG. 6, the pipeline denoted by athick line shows the pipeline through which the refrigerant (heat sourceside refrigerant and heat medium) circulates. A heat source siderefrigerant flow direction is denoted by a solid line arrow and a heatmedium flow direction by a dotted line arrow, respectively.

In the case of the cooling-main operation mode shown in FIG. 6, in theheat source apparatus 1, the four-way valve 11 is switched so as to makethe heat source side refrigerant discharged from the compressor 10 flowinto the heat source side heat exchanger 12. In the relay unit 3, thefirst pump 21 a and the second pump 21 b are driven, the stop valves 24a and 24 b are made open, the stop valves 24 c and 24 d are closed so asto make the refrigerant circulate between the first intermediate heatexchanger 15 a and the use side heat exchanger 26 a and between thesecond intermediate heat exchanger 15 b and the use side heat exchanger26 b. Under these conditions, the compressor 10 starts operation.

Firstly, the heat source side refrigerant flow in the refrigerationcycle will be explained.

A low-temperature low-pressure refrigerant is compressed by thecompressor 10 and turned into a high-temperature high-pressure gasrefrigerant to be discharged. The high-temperature high-pressure gasrefrigerant discharged from the compressor 10 passes through thefour-way valve 11 to flow into the heat source side heat exchanger 12.Then, the gas refrigerant condenses while releasing heat into theoutdoor air in the heat source side heat exchanger 12 to turn into agas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerantflowed out from the heat source side heat exchanger 12 passes throughthe check valve 13 a, flows out from the heat source apparatus 1, flowsthrough the refrigerant pipeline 4 to flow into the first relay unit 3a. The gas-liquid two-phase refrigerant flowed into the first relay unit3 a flows into the gas-liquid separator 14, being separated into a gasrefrigerant and a liquid refrigerant to flow into the second relay unit3 b.

The gas refrigerant separated by the gas-liquid separator 14 flows intothe first intermediate heat exchanger 15 a. The gas refrigerant flowedinto the first intermediate heat exchanger 15 a is condensed andliquefied while releasing heat to the heat medium circulating in theheat medium circulation circuit to turn into a liquid refrigerant. Theliquid refrigerant having flowed out from the second intermediate heatexchanger 15 b passes through the expansion valve 16 d. On the otherhand, the liquid refrigerant separated by the gas-liquid separator 14flows into the expansion valve 16 e, and merges with the liquidrefrigerant passed through the expansion valve 16 d after beingcondensed and liquefied in the first intermediate heat exchanger 15 a.Then, the refrigerant is throttled by the expansion valve 16 a toexpand, and turns into a low-temperature low-pressure gas-liquidtwo-phase refrigerant to flow into the second intermediate heatexchanger 15 b.

By absorbing heat from the heat medium circulating in the heat mediumcirculation circuit in the second intermediate heat exchanger 15 bacting as an evaporator, the gas-liquid two-phase refrigerant turns intoa low-temperature low-pressure gas refrigerant while cooling the heatmedium. The gas refrigerant flowed out from the second intermediate heatexchanger 15 b flows out from the second relay unit 3 b and first relayunit 3 a after passing via the expansion valve 16 c, passes through therefrigerant pipeline 4 to flow into the heat source apparatus 1. Therefrigerant having flowed into the heat source apparatus 1 flows throughthe check valve 13 d to be sucked into the compressor 10 again via thefour-way valve 11 and the accumulator 17. The expansion valve 16 b isadapted to have a small opening-degree such that no refrigerant flows.The expansion valve 16 c is made to be a full open state so as not tooccur pressure losses.

Next, descriptions will be given to the heat medium flow in the heatmedium circulation circuit.

In the cooling-main operation mode, since the both first and secondpumps 21 a and 21 b are driven, the heat medium circulates via the bothpipelines 5 a and 5 b. The heat medium heated by the heat source siderefrigerant in the first intermediate heat exchanger 15 a flows throughthe pipeline 5 a by the first pump 21 a. The heat medium cooled by theheat source side refrigerant in the second intermediate heat exchanger15 b flows through the pipeline 5 b by the second pump 21 b.

The heat medium having pressurized and flowed out from the first mump 21a passes through the stop valve 24 a via the flow path switching valve22 a to flow into the use side heat exchanger 26 a. Then, the heatmedium releases heat to the indoor air in the use side heat exchanger 26a to heat the air-conditioning subject area such as an inside of a roomwhere the indoor unit 2 is installed. The heat medium having pressurizedand flowed out from the second mump 21 b passes through the stop valve24 b via the flow path switching valve 22 b to flow into the use sideheat exchanger 26 b. Then, the heat medium absorbs heat from the indoorair in the use side heat exchanger 26 b to cool the air-conditioningsubject area such as an inside of a room where the indoor unit 2 isinstalled.

The heat medium having performed heating flows into the flow amountadjustment valve 25 a. Then, through the operation of the flow amountadjustment valve 25 a, only the heat medium necessary to cover theair-conditioning load required in the air-conditioning subject areaflows into the use side heat exchanger 26 a and the remaining flowsthrough the bypass 27 a so as to bypass the use side heat exchanger 26a. The heat medium passing through the bypass 27 a does not contributeto heat exchange but merges with the heat medium having passed via theuse side heat exchanger 26 a, passes through the flow path switchingvalve 23 a, flows into the first intermediate heat exchanger 15 a to besucked by the first pump 21 a again.

Likewise, the heat medium having performed cooling flows into the flowamount adjustment valve 25 b. Then, through the operation of the flowamount adjustment valve 25 b, only the heat medium necessary to coverthe air-conditioning load required in the air-conditioning subject areaflows into the use side heat exchanger 26 b and the remaining flowsthrough the bypass 27 b so as to bypass the use side heat exchanger 26b. The heat medium passing through the bypass 27 b does not contributeto heat exchange but merges with the heat medium having passed via theuse side heat exchanger 26 b, passes through the flow path switchingvalve 23 b, and flows into the second intermediate heat exchanger 15 bto be sucked by the second pump 21 b again.

Meanwhile, a warm heat medium (the heat medium used for a heating load)and a cold heat medium (the heat medium used for a cooling load) aremade to flow into the use side heat exchanger 26 a having the heatingload and the use side heat exchanger 26 b having the cooling loadwithout being mixed through the operation of the flow path switchingvalve 22 (the flow path switching valves 22 a and 22 b) and the flowpath switching valve 23 (the flow path switching valves 23 a and 23 b).The air-conditioning load required by the air-conditioning subject areasuch as an inside of a room can be covered by controlling thetemperature difference between the third temperature sensor 33 and thefourth temperature sensor 34 to keep a target value.

Thereby, since there is no need to flow the heat medium to the use sideheat exchanger 26 (including thermo-off) having no air-conditioningload, the flow path is closed by the stop valve 24 and the heat mediumis prevented from flowing into the use side heat exchanger 26. In FIG.6, while the heat medium is made to flow because in the use side heatexchangers 26 a and 26 b there is the air-conditioning load, there is noair-conditioning load in the use side heat exchangers 26 c and 26 d andthe corresponding stop valves 24 c and 24 d are made to be a closedstate. When a heating load or a cooling load is generated from the useside heat exchanger 26 c or 26 d, the stop valve 24 c or 24 d may beopened and the heat medium is made to circulate.

Heating-Main Operation Mode

FIG. 7 is a refrigerant circuit diagram showing a refrigerant flow atthe time of the heating-main operation mode of the air-conditioningapparatus 100. In FIG. 7, the heating-main operation mode will beexplained by a case where a heating load is generated in the use sideheat exchangers 26 a and a cooling load is generated in the use sideheat exchangers 26 b, as an example. That is, FIG. 7 illustrates a casewhere neither heating load nor cooling load are generated in the useside heat exchangers 26 c and 26 d. In FIG. 7, the pipeline denoted by athick line shows the pipeline through which the refrigerant (heat sourceside refrigerant and heat medium) circulates. A heat source siderefrigerant flow direction is denoted by a solid line arrow and a heatmedium flow direction by a dotted line arrow, respectively.

In the case of the heating-main operation mode shown in FIG. 7, in theheat source apparatus 1, the four-way valve 11 is switched so as to makethe heat source side refrigerant discharged from the compressor 10 flowinto the relay unit 3 without via the heat source side heat exchanger12. In the relay unit 3, the first pump 21 a and the second pump 21 bare driven, the stop valves 24 a and 24 b are made open, the stop valves24 c and 24 d are closed so as to make the heat medium circulate betweenthe first intermediate heat exchanger 15 a and the use side heatexchanger 26 a and between the second intermediate heat exchanger 15 band the use side heat exchanger 26 b. Under these conditions, thecompressor 10 starts operation.

Firstly, the heat source side refrigerant flow in the refrigerationcycle will be explained.

A low-temperature low-pressure refrigerant is compressed by thecompressor 10 and turned into a high-temperature high-pressure gasrefrigerant to be discharged. The high-temperature high-pressure gasrefrigerant discharged from the compressor 10 passes through thefour-way valve 11, flows through the first connection pipeline 4 a,passes through the check valve 13 b to flow out from the heat sourceapparatus 1. The high-temperature high-pressure gas refrigerant havingflowed out from the heat source apparatus 1 passes through therefrigerant pipeline 4 a to flow into the first relay unit 3 a. Thehigh-temperature high-pressure gas refrigerant having flowed into thefirst relay unit 3 a flows into the first intermediate heat exchanger 15a after flowing into the intermediate heat exchanger 14. Thehigh-temperature high-pressure gas refrigerant having flowed into thefirst intermediate heat exchanger 15 a condenses and liquefies whilereleasing heat to the heat medium circulating in the heat mediumcirculation circuit to turn into a high-pressure liquid refrigerant.

The high-pressure liquid refrigerant having flowed out from the firstintermediate heat exchanger 15 a is throttled by the expansion valve 16d and expanded to turn into a low-temperature low-pressure gas-liquidtwo-phase state. The gas-liquid two-phase state refrigerant throttled bythe expansion valve 16 d is branched into the flow path passing throughthe expansion valve 16 a and the flow path passing through the expansionvalve 16 b. The refrigerant having passed via the expansion valve 16 ais further expanded by the expansion valve 16 a, turns into alow-temperature low-pressure gas-liquid two-phase refrigerant to flowinto the second intermediate heat exchanger 15 b acting as anevaporator. The refrigerant having flowed into the second intermediateheat exchanger 15 b absorbs heat from the heat medium therein to turninto a low-temperature low-pressure gas refrigerant. The low-temperaturelow-pressure gas refrigerant having flowed out from the secondintermediate heat exchanger 15 b passes via the expansion valve 16 c.

On the other hand, the refrigerant having throttled by the expansionvalve 16 d and flowed into the expansion valve 16 b merges with therefrigerant having passed via the second intermediate heat exchanger 15b and the expansion valve 16 c to turn into a low-temperaturelow-pressure refrigerant having larger dryness. Then, the mergedrefrigerant flows out from the second relay unit 3 b and the first relayunit 3 a, and passes through the refrigerant pipeline 4 to flow into theheat source apparatus 1. The refrigerant having flowed into the heatsource apparatus 1 passes through the second connection pipeline 4 b viathe check valve 13 c to flow into the heat source side heat exchanger 12acting as an evaporator. Then, the refrigerant having flowed into theheat source side heat exchanger 12 absorbs heat from the outdoor airtherein to turn into a low-temperature low-pressure gas refrigerant. Thelow-temperature low-pressure gas refrigerant having flowed out from theheat source side heat exchanger 12 returns to the compressor 10 via thefour-way valve 11 and accumulator 17. The expansion valve 16 e isadapted to have a small opening degree such that no refrigerant flows.

Next, descriptions will be given to the heat medium flow in the heatmedium circulation circuit.

In the heating-main operation mode, since both the first pump 21 a andthe second pump 21 b are driven, the heat medium circulates via bothpipelines 5 a and 5 b. The heat medium having heated by the heat sourceside refrigerant in the first intermediate heat exchanger 15 a flows inthe pipeline 5 a by the first pump 21 a. The heat medium having beencooled by the heat source side refrigerant in the second intermediateheat exchanger 15 b flows in the pipeline 5 b by the second pump 21 b.

The heat medium having pressurized in and flowed out from the first pump21 a passes through the stop valve 24 a via the flow path switchingvalve 22 a to flow into the use side heat exchanger 26 a. Then, the heatmedium releases heat to the indoor air therein to heat theair-conditioning subject area of such as an inside of a room where theindoor unit 2 is installed. The heat medium having pressurized in andflowed out from the second pump 21 b passes through the stop valve 24 bvia the flow path switching valve 22 b to flow into the use side heatexchanger 26 b. Then, the heat medium absorbs heat from the indoor airtherein to cool the air-conditioning subject area of such as an insideof a room where the indoor unit 2 is installed.

The heat medium having flowed out from the use side heat exchanger 26 aflows into the flow amount adjustment valve 25 a. Then, through theoperation of the flow amount adjustment valve 25 a, only the heat mediumnecessary to cover the air-conditioning load required in theair-conditioning subject area such as an inside of a room flows into theuse side heat exchanger 26 a and the remaining heat medium flows throughthe bypass 27 so as to bypass the use side heat exchanger 26 a. The heatmedium passing through the bypass 27 a does not contribute to heatexchange, merges with the heat medium having passed via the use sideheat exchanger 26 a, passes through the flow path switching valve 23 a,and flows into the first intermediate heat exchanger 15 a to be suckedinto the second pump 21 a again.

Likewise, the heat medium having flowed out from the use side heatexchanger 26 b flows into the flow amount adjustment valve 25 b. Then,through the operation of the flow amount adjustment valve 25 b, only theheat medium necessary to cover the air-conditioning load required in theair-conditioning subject area such as an inside of a room flows into theuse side heat exchanger 26 b and the remaining heat medium flows throughthe bypass 27 b so as to bypass the use side heat exchanger 26 b. Theheat medium passing through the bypass 27 b does not contribute to heatexchange, merges with the heat medium having passed via the use sideheat exchanger 26 b, passes through the flow path switching valve 23 b,and flows into the second intermediate heat exchanger 15 b to be suckedinto the second pump 21 b again.

Meanwhile, a warm heat medium and a cold heat medium are made to flowinto the use side heat exchanger 26 a having the heating load and theuse side heat exchanger 26 b having the cooling load without being mixedthrough the operation of the flow path switching valve 22 (the flow pathswitching valves 22 a and 22 b) and the flow path switching valve 23(the flow path switching valves 23 a and 23 b). The air-conditioningload required by the air-conditioning subject area such as an inside ofa room can be covered by controlling the temperature difference betweenthe third temperature sensor 33 and the fourth temperature sensor 34 tokeep a target value.

Thereby, since there is no need to flow the heat medium to the use sideheat exchanger 26 (including thermo-off) having no air-conditioningload, the flow path is closed by the stop valve 24 and the heat mediumis prevented from flowing into the use side heat exchanger 26. In FIG.7, while the heat medium is made to flow because in the use side heatexchangers 26 a and 26 b there is the air-conditioning load, there is noair-conditioning load in the use side heat exchangers 26 c and 26 d andthe corresponding stop valves 24 c and 24 d are made to be a closedstate. When a heating load or a cooling load is generated from the useside heat exchanger 26 c or 26 d, the stop valve 24 c or 24 d may beopened and the heat medium may be made to circulate.

As mentioned above, when the heating load is generated in the use sideheat exchangers 26 a to 26 d, by switching the corresponding flow pathswitching valves 22 a to 22 d and the flow path switching valves 23 a to23 d to the flow path connected with the first intermediate heatexchanger 15 a, and when the cooling load is generated in the use sideheat exchangers 26 a to 26 d, by switching the corresponding flow pathswitching valves 22 a to 22 d and the flow path switching valves 23 a to23 d to the flow path connected with the second intermediate heatexchanger 15 b, heating operation or cooling operation can be freelyperformed in each indoor unit 2.

The flow path switching valves 22 a to 22 d and the flow path switchingvalves 23 a to 23 d may be, in addition to those that can switch threeflow paths such as a three-way valve, those that can switch flow pathssuch as a combination of two sets of those that open and close atwo-direction flow path such as an on-off valve. Further, those that canchange the flow amount of a three-way flow path such as a stepping motordrive type mixing valve and those that can change the flow amount of atwo-way flow path such as an electronic expansion valve may be used incombination as a flow path switching valve, and in that case waterhammer can be prevented caused by a sudden opening or closing of theflow path.

The air-conditioning load in the use side heat exchangers 26 a to 26 dcan be expressed by the formula (1) as follows and becomes a product ofthe flow amount, density, and constant pressure specific heat of theheat medium by the temperature difference of the heat medium at theinlet and outlet of the use side heat exchangers 26 a to 26 d. Here, Vwdenotes the flow amount of the heat medium, ρw the density of the heatmedium, Cpw the constant pressure specific heat of the heat medium, Twthe temperature of the heat medium, a suffix “in” the value at the heatmedium inlet of the use side heat exchangers 26 a to 26 d, the suffix“out” the value at the heat medium outlet of the use side heatexchangers 26 a to 26 d, respectively.

Formula 1

Q=V _(w)*(ρ_(win) *Cp _(win) *T _(win)−ρ_(wout) *Cp _(wout) *T_(wout))˜V _(w)*ρ_(w) *Cp _(w)*(T _(win) −T _(wout))  (1)

That is, when the heat medium flow amount made to flow into the use sideheat exchangers 26 a to 26 d is constant, the temperature difference atthe heat medium inlet/outlet varies according to the change inair-conditioning load in the use side heat exchangers 26 a to 26 d. Withthe temperature difference at the inlet/outlet of the use side heatexchangers 26 a to 26 d being a target, by controlling the flow amountadjustment valves 25 a to 25 d so that the difference approaches thetarget value, it is possible to make an excess heat medium flow into thebypasses 27 a to 27 d and control the flow amount flowing into the useside heat exchangers 26 a to 26 d. The target value of the temperaturedifference at the inlet/outlet of the use side heat exchangers 26 a to26 d is set at 5 degrees C., for example.

In FIGS. 3 to 7, although descriptions are given to a case where theflow amount adjustment valves 25 a to 25 d are a mixing valve installedat the downstream side of the use side heat exchangers 26 a to 26 d, asan example, the use side heat exchangers 26 a to 26 d may be installedat the upstream side.

The heat medium that has exchanged heat with the use side heatexchangers 26 a to 26 d and the heat medium having passed through thebypasses 27 a to 27 d with no heat exchange and no change in temperaturemerge at a merging point thereafter. At the merging point, the formula(2) as follows holds. Here, Tw_(in) and Tw_(out) denote the heat mediumtemperature in the inlet and outlet of the use side heat exchangers 26 ato 26 d, Vw the heat medium flow amount flowing into the flow amountadjustment valves 25 a to 25 d, Vwr the heat medium flow amount flowinginto the use side heat exchangers 26 a to 26 d, and Tw the heat mediumtemperature after the merging of the heat medium having flowed throughthe use side heat exchangers 26 a to 26 d and the heat medium havingflowed through the bypasses 27 a to 27 d, respectively.

Formula 2

T _(w)=(V _(wr) /V _(w))*T _(wout)+(1−V _(wr) /V _(w))*T _(win)  (2)

That is, when the heat medium having exchanged heat with the use sideheat exchangers 26 a to 26 d and being subjected temperature change andthe heat medium having passed through the bypasses 27 a to 27 d with noheat exchange and no change in temperature merge, the temperaturedifference of the heat medium approaches the inlet temperature of theuse side heat exchangers 26 a to 26 d by a by-passed flow amount. Forexample, when the total flow amount is 20 L/min, the heat medium inlettemperature of the use side heat exchangers 26 a to 26 d 7 degrees C.,the outlet temperature 13 degrees C., and the flow amount made to flowto the use side heat exchangers 26 a to 26 d side 10 L/min, thetemperature after the merging becomes 10 degrees C. by the formula (2).

Now, the heat media of the merged temperature return from each indoorunit 2 and are merged to flow into the first intermediate heat exchanger15 a and the second intermediate heat exchanger 15 b. Thereby, if theheat exchange amount is not changed in the first intermediate heatexchanger 15 a or the second intermediate heat exchanger 15 b, thetemperature differences at the inlet and outlet become almost the samethrough the heat exchange in the first intermediate heat exchanger 15 aor the second intermediate heat exchanger 15 b.

That is, suppose that the inlet/outlet temperature difference of thefirst intermediate heat exchanger 15 a or the second intermediate heatexchanger 15 b is 6 degrees C. and originally, the inlet temperature is13 degree C. and outlet temperature is 7 degrees C. in the firstintermediate heat exchanger 15 a or the second intermediate heatexchanger 15 b. Then, the air-conditioning load decreases in the useside heat exchangers 26 a to 26 d and the inlet temperature is loweredto 10 degrees C. of the first intermediate heat exchanger 15 a or thesecond intermediate heat exchanger 15 b. Then, if nothing is done, sincethe first intermediate heat exchanger 15 a or the second intermediateheat exchanger 15 b exchanges heat of almost the same amount, the heatmedium flows out from the first intermediate heat exchanger 15 a or thesecond intermediate heat exchanger 15 b at 4 degrees C., which isrepeated to cause the temperature to be decreased little by little.

In order to prevent the above, the rotation speed of the pump, which isthe first pump 21 a and the second pump 21 b, may be varied according tothe change in the air-conditioning load of the use side heat exchangers26 a to 26 d so that the heat medium outlet temperature of the firstintermediate heat exchanger 15 a or the second intermediate heatexchanger 15 b detected by the first temperature sensors 31 a and 31 bapproaches the target value. Thereby, when the air-conditioning load isdecreased, the rotation speed of the pump is lowered to result inenergy-saving, and when the air-conditioning load is increased, therotation speed of the pump is raised so that the air-conditioning loadcan be covered.

The second pump 21 b is made to be driven when cooling load ordehumidifying load occurs in any of the use side heat exchangers 26 a to26 d and stopped when there is neither cooling load nor dehumidifyingload in every use side heat exchanger 26 a to 26 d.

The first pump 21 a is made to be driven when heating load occurs in anyof the use side heat exchangers 26 a to 26 d and stopped when there isno heating load in every use side heat exchanger 26 a to 26 d.

Next, a case where each operation mode described above is made to stopwill be considered. It is assumed that operation stop instruction isissued from a remote controller. Then, the air flow is made to stop bystopping the fan attached to each indoor unit 2 and the refrigerant flowis made to stop by stopping the compressor 10. In general, since theindoor unit 2 and the heat source apparatus 1 are controlled by separatecontrollers, all indoor units 2 are not necessarily connected with asingle remote controller, and in one indoor unit 2 or in one room, asingle remote controller is often installed.

In the conventional air-conditioning apparatus, since the refrigerant(heat source side refrigerant) is made to circulate in all the use sideheat exchangers, when a stop instruction is input from the remotecontroller, it is arranged that the fan of the corresponding indoor unitis stopped firstly, the solenoid valves and the electronic expansionvalves or the like are operated, and the refrigerant flow to each indoorunit is stopped. Then, according to the stop instruction from the remotecontroller corresponding to the indoor unit operated last, the fan ofthe corresponding indoor unit is stopped, the refrigerant flow path isclosed, and thereafter the compressor 10 is stopped.

On the other hand, in the air-conditioning apparatus 100 according toEmbodiment 1, the refrigerant delivered from the heat source apparatus 1exchanges heat with the heat medium in the intermediate heat exchanger15 and the heat medium is adapted to flow in the pipeline 5 of the useside heat exchangers 26 a to 26 d. Like the conventionalair-conditioning apparatus, it is considered that when the stopinstruction is issued to all the indoor units 2 under these conditions,the corresponding fan may be stopped, the flow path of the heat mediummay be closed by the stop valve 24, thereafter the pump 21 may bestopped, and the compressor 10 may be stopped.

However, in the case where the air-conditioning apparatus is stoppedunder such a order, since the pump 21 is not in operation when thecompressor 10 is stopped. Therefore, when the stop of the compressor 10is delayed, because no heat medium flows in the intermediate heatexchanger 15, the temperature of the heat medium in this portionabruptly increases or decreases, the high-pressure of the compressor 10abruptly increases or the low-pressure abruptly decreases in response tothat, possibly resulting in abnormal stop. In particular, when thesecond intermediate heat exchanger 15 b operates as an evaporator, theheat medium in the first intermediate heat exchanger 15 a and the secondintermediate heat exchanger 15 b freezes, supposedly damaging the firstintermediate heat exchanger 15 a and the second intermediate heatexchanger 15 b. Consequently, each operation mode is desirably stoppedaccording to the procedure as follows.

FIG. 8 is a flowchart showing the processing flow at the time ofstopping each operation mode. Based on FIG. 8, stop of each operationmode will be explained. The controller 60 starts processing to stop eachoperation mode by the stop instruction input from the remote controller(FT0). Firstly, the controller 60 stops the fan of the correspondingindoor unit 2 (FT1). Then, the controller 60 judges whether the indoorunit 2 to be stopped is the indoor unit 2 to be stopped last (FT2). Whenthe controller 60 judges that the indoor unit 2 to be stopped is not theindoor unit 2 to be stopped last (FT2: No), the corresponding stop valve24 is closed and the heat medium flow into each indoor unit 2 is stopped(FT7).

On the other hand, when the controller 60 judges that the indoor unit 2to be stopped is the indoor unit 2 to be stopped last (FT2: Yes), thecompressor 10 is made to stop (FT3). Thereafter, the controller 60judges the operation mode in execution (FT4). When the controller 60judges that it is cooling or dehumidifying operation mode (an operationmode in which only cooling load or dehumidifying load is generated inany of the use side heat exchanger 26) (FT4: cooling/dehumidifying), thesecond pump 21 b is made to stop (FT5).

When the controller 60 judges that it is heating operation mode (anoperation mode in which only heating load is generated in any of useside heat exchangers 26) (FT4: heating), the first pump 21 a is made tostop (FT6). That is, the controller 60 stops the first pump 21 a or thesecond pump 21 b according to the operation mode. Finally, thecontroller 60 closes the corresponding stop valve 24 to stop the heatmedium flow to each indoor unit 2 (FT7). Then, processing at the time ofstopping each operation mode is terminated (FT8).

When each operation mode is stopped as mentioned above, since the firstpump 21 a or the second pump 21 b is in operation when the compressor 10stops, a first heat medium circulates in the first intermediate heatexchanger 15 a or the second intermediate heat exchanger 15 b, causingno abnormal change in the high-pressure and low-pressure of thecompressor 10. When all the stop valves 24 a to 24 d are closed prior tothe stop of the first pump 21 a or the second pump 21 b, the circulationpath of the heat medium is closed. Therefore, since the operation of thefirst pump 21 a or the second pump 21 b cannot be continued, the laststop valve 24 is made to close after both first and second pumps 21 aand 21 b are stopped.

When it is possible to stop the compressor 10 and the first pump 21 a orthe second pump 21 b almost at the same time, they may be stopped almostsimultaneously. The term almost simultaneously here means that that theymay be stopped at the same time, or even if the stop of the first pump21 a or the second pump 21 b may be a little earlier, the stop of thecompressor 10 right after thereof is included within a short timeperiod, for example, within one second or two seconds so that no affectis caused in the high-pressure or low-pressure of the refrigerationcycle. The temporal context of the stop valves 24 a to 24 d and thefirst pump 21 a or the second pump 21 b is the same.

FIG. 9 is a flowchart showing the processing flow at the time ofstarting each operation mode. Based on FIG. 9, descriptions will begiven to start of each operation mode. The controller 60 startsprocessing to start each operation mode by the operation instructioninput from the remote controller (GT0). Firstly, the controller 60 opensthe stop valve 24 corresponding to the use side heat exchanger 26 to beoperated to secure the heat medium flow path (GT1). Then, the controller60 judges whether the indoor unit 2 to be started is the indoor unit 2to be firstly started (GT2). When judging that the indoor unit 2 to bestarted is not the indoor unit 2 to be firstly started (GT2; No),processing is terminated (GT7).

On the other hand, when the controller 60 judges that the indoor unit 2to be started is the indoor unit 2 to be firstly started (GT2; Yes), theoperation mode to be executed is judged (GT3). When the controller 60judges that it is cooling or dehumidifying operation mode (GT3;cooling/dehumidifying), the second pump 21 b is made to operate (GT4).When the controller 60 judges that the operation mode to be executed isthe heating operation mode (GT4; heating), the first pump 21 a is madeto operate (GT5). That is, the controller 60 operates either the firstpump 21 a or the second pump 21 b according to the operation mode. Thecontroller 60 finally operates the compressor 10 after securing the heatsource of the compressor 10 (GT6). Then, processing at the time ofstarting each operation mode is terminated (GT7).

Although the fan of the indoor unit 2 is not shown, it is adapted to besimultaneously started with the start instruction at the time of thecooling operation mode and to be operated after the heat mediumtemperature has risen to some degree at the time of heating operationmode. When it is possible to start the compressor 10 and the first pump21 a or the second pump 21 b almost at the same time, they may bestarted almost simultaneously. The term almost simultaneously here meansthat that they may be started at the same time, or even if the start ofthe compressor 10 may be a little earlier, the start of the first pump21 a or the second pump 21 b right after thereof is included within ashort time period, for example, within one second or two seconds so thatno affect is caused in the high-pressure or low-pressure of therefrigeration cycle. The temporal context of the stop valves 24 a to 24d and the first pump 21 a or the second pump 21 b is the same.

FIG. 10 is a flowchart showing the processing flow at the time ofswitching from the cooling-main operation mode to the cooling onlyoperation mode. Based on FIG. 10, descriptions will be given to theprocessing flow at the time of switching from the cooling-main operationmode to the cooling only operation mode. At the time of thecooling-heating simultaneous operation in which cooling operation andheating operation are mixed, that is, at the time of switching operationfrom the cooling-main operation mode or the heating-main operation,switching should be performed while paying attention to the order ofON/OFF of the compressor 10 and the pump 21.

The controller 60 starts processing at the time of switching fromcooling-main operation mode to the cooling only operation mode by theoperation instruction input from the remote controller (HT0). That is,the controller 60 switches the heat source side refrigerant flow at therefrigeration cycle side from cooling-main operation mode to the coolingonly operation mode (HT1). Thereafter, the controller 60 stops the firstpump 21 a at the heating side, which is a pump not corresponded to theoperation mode (here, cooling only operation mode) after the switching(HT2). When the first pump 21 a is stopped prior to the switching of theoperation mode, high-pressure of the refrigerant increases and operationefficiency is deteriorated, possibly resulting in an abnormal stop.

However, by switching operation modes in such an order mentioned above,mode switching can be performed safely. The controller 60 closes thestop valve 24 corresponding to the indoor unit 2 that performed heatingoperation lastly after stopping the first pump 21 a to close the flowpath of the heat medium (HT3). Then, processing at the time of switchingfrom the cooling-main operation mode to the cooling only operation modeis terminated (HT4).

FIG. 11 is a flowchart showing the processing flow at the time ofswitching from the heating-main operation mode to the heating onlyoperation mode. Based on FIG. 11, descriptions will be given to theprocessing flow at the time of switching from the heating-main operationmode to the heating only operation mode. As explained in FIG. 10, at thetime of the cooling-heating simultaneous operation in which coolingoperation and heating operation are mixed, that is, at the time ofswitching operation mode from the cooling-main operation mode or theheating-main operation, switching should be performed while payingattention to the order of ON/OFF of the compressor 10 and the pump 21.

The controller 60 starts processing at the time of switching from theheating-main operation mode to the heating only operation mode by theoperation instruction input from the remote controller (KT0). That is,the controller 60 switches the heat source side refrigerant flow at therefrigeration cycle side from the heating-main operation mode to theheating only operation mode (KT1). Thereafter, the controller 60 stopsthe second pump 21 b at the cooling side, which is a pump notcorresponded to the operation mode (here, the heating only operationmode) after the switching (KT2). When the second pump 21 b is stoppedprior to the switching of the operation mode, since the heat source toevaporate the refrigerant disappears, the low-pressure of therefrigerant decreases, possibly resulting in freezing of the heatmedium.

However, by switching operation modes in such an order mentioned above,mode switching can be performed safely. The controller 60 closes thestop valve 24 corresponding to the indoor unit 2 that performed coolingoperation lastly after stopping the second pump 21 b to close the heatmedium flow path (KT3). Then, processing at the time of switching fromthe heating-main operation mode to the heating only operation mode isterminated (HT4).

At the time of switching explained in FIGS. 10 and 11, when it ispossible to perform switching of the operation mode and the stop of thefirst pump 21 a or the second pump 21 b almost at the same time, theymay be performed almost simultaneously. The term almost simultaneouslyhere means that that they may be performed exactly at the same time, oreven if the stop of the first pump 21 a or the second pump 21 b may be alittle earlier, the switching of the operation mode right after thereofis included within a short time period, for example, within one secondor two seconds so that no affect is caused in the high-pressure orlow-pressure of the refrigeration cycle. The temporal context of thestop valves 24 a to 24 d and the first pump 21 a or the second pump 21 bis the same.

FIG. 12 is a flowchart showing the processing flow at the time ofswitching from the cooling only operation mode to the cooling-mainoperation mode. Based on FIG. 12, descriptions will be given to theprocessing flow at the time of switching from the cooling only operationmode to the cooling-main operation mode. At the time of thecooling-heating simultaneous operation in which cooling operation andheating operation are mixed, that is, at the time of switching operationmode to cooling-main operation mode or heating-main operation, switchingshould be performed while paying attention to the order of ON/OFF of thecompressor 10 and the pump 21.

The controller 60 starts processing at the time of switching fromcooling only operation mode to cooling-main operation mode by theoperation instruction input from the remote controller (LT0). That is,the controller 60 opens the stop valve 24 corresponding to the indoorunit 2 that performs heating operation firstly (LT1). Then, thecontroller 60 starts the first pump 21 a at the heating side (LT2).Then, the controller 60 switches the operation mode to be stopped tocooling-main operation mode (LT3).

When the operation mode is switched prior to the start of the first pump21 a, high-pressure of the refrigerant increases and operationefficiency is deteriorated, possibly resulting in an abnormal stop.However, by performing switching in such an order mentioned above, modeswitching can be performed safely. As shown in LT1, the stop valve 24corresponding to the indoor unit 2 having a heating load has to be madeopen before starting the first pump 21 a and the flow path of the heatmedium has to be secured.

FIG. 13 is a flowchart showing the processing flow at the time ofswitching from the heating only operation mode to the heating-mainoperation mode. Based on FIG. 13, descriptions will be given to theprocessing flow at the time of switching from heating only operationmode to the heating-main operation mode. At the time of thecooling-heating simultaneous operation in which cooling operation andheating operation are mixed, that is, at the time of switching operationmode to cooling-main operation mode or heating-main operation, switchingshould be performed while paying attention to the order of ON/OFF of thecompressor 10 and the pump 21.

The controller 60 starts processing at the time of switching fromheating only operation mode to heating-main operation mode by theoperation instruction input from the remote controller (R10). That is,the controller 60 opens the stop valve 24 corresponding to the indoorunit 2 that performs cooling operation firstly (RT1). Then, thecontroller 60 starts the second pump 21 b at the cooling side (RT2).Then, the controller 60 switches the operation mode to be stopped toheating-main operation mode (RT3).

When the operation mode is switched prior to the start of the secondpump 21 b, since there is no heat source to evaporate the refrigerant,low-pressure of the refrigerant decreases, possibly resulting infreezing of the heat medium. However, by performing switching in such anorder mentioned above, mode switching can be performed safely. As shownin RT1, the stop valve 24 corresponding to the indoor unit 2 having acooling load has to be made open before starting the second pump 21 band the flow path of the heat medium has to be secured.

At the time of the switching explained in FIGS. 12 and 13, when it ispossible to perform switching of the operation mode and the start of thefirst pump 21 a or the second pump 21 b almost at the same time, theymay be performed almost simultaneously. The term almost simultaneouslyhere means that that they may be performed at the same time, or even ifthe switching of the operation mode may be a little earlier, the startof the first pump 21 a or the second pump 21 b is included right afterwithin a short time period, for example, within one second or twoseconds so that no affect is caused in the high-pressure or low-pressureof the refrigeration cycle. The temporal context of the stop valves 24 ato 24 d and the first pump 21 a or the second pump 21 b is the same.

As mentioned above, in the air-conditioning apparatus 100 according toEmbodiment 1, the stop, start or the switching of the operation mode ofthe compressor 10 is performed during the stop, start or the switchingof the operation mode of the system with the heat medium beingcirculated in the intermediate heat exchanger 15. Thereby, it ispossible to have stable operation, to prevent the refrigeration cycleoperation efficiency from being deteriorated such that high-pressure ofthe refrigerant becoming high or low, and to improve system efficiency,achieving energy-saving.

That is, by performing stop control and start control, theair-conditioning apparatus 100 does not fall into poor efficiencyoperation conditions such that high-pressure increases or low-pressuredecreases of the refrigeration cycle, can make the operation efficiencyof the entire system including start and stop improve to achieve highenergy-saving. When switching from cooling-main operation mode toheating-main operation mode or heating-main operation mode tocooling-main operation mode, since the first pump 21 a and the secondpump 21 b are in operation in either operation mode, they can beswitched as they are.

As mentioned above, since the air-conditioning apparatus 100 accordingto Embodiment 1 is adapted to transfer the heating energy and/or thecooling energy of the refrigeration cycle to the use side heat exchanger26 via two or more intermediate heat exchangers 15, the outdoor sidehousing (the heat source apparatus 1) can be installed in the outdoorspace 6 at the outdoor side, the indoor side housing (the indoor unit 2)in the indoor side living space 7, and the heat medium conversionhousing (the relay unit 3) in the non-living space 50, respectively.Therefore, the heat source side refrigerant can be suppressed fromflowing into the living space 7 and safety and reliability of the systemcan be improved.

In the air-conditioning apparatus 100, since the heat medium such aswater and brine is allowed to flow through the heat medium circulationcircuit, it is possible to reduce the heat source side refrigerantamount and to mitigate the influence on the environment at the time ofthe refrigerant leaking. Further, by connecting the relay unit 3 and twoor more indoor units 2 with two heat medium pipelines (the pipeline 5)respectively, the air-conditioning apparatus 100 can reduce carryingpower of water, facilitating energy-saving and easy installation work.

Embodiment 2

FIG. 14 is a circuit diagram showing a circuit configuration of theair-conditioning apparatus 200 according Embodiment 2. Based on FIG. 14,the circuit configuration of the air-conditioning apparatus 200 will beexplained. The air-conditioning apparatus 200 performs cooling operationor heating operation using the refrigeration cycle (the refrigerationcycle and the heat medium circulation circuit) that circulates therefrigerant (the heat source side refrigerant and the heat medium) likethe air-conditioning apparatus 100. The air-conditioning apparatus 200differentiates the configuration of the flow amount adjustment valves125 a to 125 d corresponding to the flow amount adjustment valves 25 ato 25 d from the air-conditioning apparatus 100 according toEmbodiment 1. In Embodiment 2, descriptions will be given focusing ondifferences from Embodiment 1, the same signs will be provided with thesame portions as Embodiment 1, and descriptions will be omitted.

Relay Unit 3

The relay unit 3 is provided with four flow amount adjustment valves125. The relay unit 3 is provided with neither bypass 27 nor stop valve24. That is, since in the air-conditioning apparatus 200, the flowamount adjustment valve 125 is constituted by a two-way flow pathadjustment valve, the bypass 27 connecting the pipeline 5 and the flowamount adjustment valve 125 between the stop valve 24 and the use sideheat exchanger 26 and the stop valve 24 that opens and closes the heatmedium flow path become unnecessary. Other configurations of theair-conditioning apparatus 200 are the same as those of theair-conditioning apparatus 100 according to Embodiment 1.

The four flow amount adjustment valves 125 (the flow amount adjustmentvalves 125 a to 125 d) are constituted by two-way flow path adjustmentvalves and switch the heat medium flow path. The flow amount adjustmentvalve 125 is adapted to be provided for the number (it is four, here)corresponding to the number of the installed indoor units 2. The flowamount adjustment valve 125 is connected with the use side heatexchanger 26 in one side and with the flow path switching valve 23 inthe other side respectively and provided at the outlet side of the heatmedium flow path of the use side heat exchanger 26.

In this case, since the heat medium flow path can be closed by the flowamount adjustment valves 25 a to 25 d, there is no need to install thestop valves 24 a to 24 d. Therefore, the stop valve 24 may be replacedby the flow amount adjustment valve 25. By making them correspond withthe indoor units 2, they are illustrated as flow amount adjustmentvalves 125 a, 125 b, 125 c, and 125 d from under this sheet. The flowamount adjustment valve 125 corresponds with the flow amount adjustmentvalve 25 of the air-conditioning apparatus 100 according to Embodiment1.

Here, operations of the air-conditioning apparatus 200 will beexplained. FIG. 15 is a flowchart showing the processing flow at thetime of stopping each operation mode. Based on FIG. 15, the stop of eachoperation mode will be explained. The controller 60 starts processing tostop each operation mode by the stop instruction input from the remotecontroller (ST1). Firstly, the controller 60 stops the fan of thecorresponding indoor unit 2 (ST1). Then, the controller 60 judgeswhether the indoor unit 2 to be stopped is the indoor unit 2 to belastly stopped (ST2). When the controller 60 judges that the indoor unit2 to be stopped is not the indoor unit 2 to be lastly stopped (ST2: No),the corresponding stop valve 125 is set at an extremely small openingarea such that no heat medium flows therethrough and the heat mediumflow into each indoor unit 2 is made to stop (ST7).

On the other hand, when the controller 60 judges that the indoor unit 2to be stopped is the indoor unit 2 to be lastly stopped (ST2: Yes), thecompressor 10 is made to stop (ST3). Thereafter, the controller 60judges the operation mode having been in execution (ST4). When thecontroller 60 judges that it is cooling or dehumidifying operation mode(an operation mode in which only cooling load or dehumidifying load isgenerated in any of the use side heat exchangers 26) (ST4:cooling/dehumidifying), the second pump 21 b is made to stop (ST5).

When the controller 60 judges that it is heating operation mode (anoperation mode in which only heating load is generated in any of the useside heat exchangers 26) (ST4: heating), the first pump 21 a is made tostop (ST6). That is, the controller 60 stops either the first pump 21 aor the second pump 21 b according to the operation mode. Finally, thecontroller 60 sets the corresponding stop valve 125 at an extremelysmall opening area such that no heat medium flows therethrough and theheat medium flow into each indoor unit 2 is made to stop (ST7). And theprocessing at the time of stopping each operation mode is terminated(ST8).

If each operation mode is stopped as mentioned above, since the firstpump 21 a or the second pump 21 b is in operation when the compressor 10is stopped, a first refrigerant circulates in the first intermediateheat exchanger 15 a or the second intermediate heat exchanger 15 b,causing no abnormal change in the high-pressure and low-pressure in thecompressor 10. When all the stop valves 125 a to 125 d are closed priorto the stop of the first pump 21 a or the second pump 21 b, thecirculation path of the heat medium is closed. Therefore, since theoperation of the first pump 21 a or the second pump 21 b cannot becontinued, the last stop valve 125 is made to close after both first andsecond pumps 21 a and 21 b are stopped.

When it is possible to stop the compressor 10 and the first pump 21 a orthe second pump 21 b almost at the same time, they may be stopped almostsimultaneously. The definition of the term almost simultaneously is thesame as Embodiment 1.

FIG. 16 is a flowchart showing the processing flow at the time ofstarting each operation mode. Based on FIG. 16, descriptions will begiven to start of each operation mode. The controller 60 startsprocessing to start each operation mode by the operation instructioninput from the remote controller (UT0). Firstly, the controller 60 opensthe stop valve 125 corresponding to the use side heat exchanger 26 to beoperated to secure the heat medium flow path (UT1). Then, the controller60 judges whether the indoor unit 2 to be started is the indoor unit 2to be firstly started (UT2). When judging that the indoor unit 2 to bedriven is not the indoor unit 2 to be firstly started (UT2; No),processing is terminated (UT7).

On the other hand, when the controller 60 judges that the indoor unit 2to be started is the indoor unit 2 to be firstly started (UT2; Yes), itjudges the operation mode to be executed (UT3). When the controller 60judges that it is cooling or dehumidifying operation mode (UT3;cooling/dehumidifying), the second pump 21 b is made to operate (UT4).When the controller 60 judges that it is heating operation mode (UT4;heating), the first pump 21 a is made to operate (UT5). That is, thecontroller 60 operates either the first pump 21 a or the second pump 21b according to the operation mode. The controller 60 finally operatesthe compressor 10 after securing the heat source of the compressor 10(UT6). Then, processing at the time of starting each operation mode isterminated (UT7).

Although the fan of the indoor unit 2 is not shown, it is adapted to besimultaneously started with the start instruction at the time of coolingoperation mode and to be operated after the heat medium temperature hasrisen to some degree at the time of heating operation mode. When it ispossible to start the compressor 10 and the first pump 21 a or thesecond pump 21 b almost at the same time, they may be started almostsimultaneously. The definition of the term almost simultaneously is thesame as that of Embodiment 1.

FIG. 17 is a flowchart showing the processing flow at the time ofswitching from cooling-main operation mode to cooling only operationmode. Based on FIG. 17, descriptions will be given to the processingflow at the time of switching from cooling-main operation mode tocooling only operation mode. At the time of cooling-heating simultaneousoperation in which cooling operation and heating operation are mixed,that is, at the time of switching operation from cooling-main operationmode or heating-main operation, switching should be performed whilepaying attention to the order of ON/OFF of the compressor 10 and thepump 21.

The controller 60 starts processing at the time of switching fromcooling-main operation mode to cooling only operation mode by theoperation instruction input from the remote controller (VT0). That is,the controller 60 switches the heat source side refrigerant flow at therefrigeration cycle side from cooling-main operation mode to coolingonly operation mode (VT1). Then, the controller 60 stops the first pump21 a at the heating side (HT2). When the first pump 21 a is stoppedprior to the switching of the operation mode, high-pressure of therefrigerant increases and operation efficiency is deteriorated, possiblyresulting in an abnormal stop.

However, by switching operation modes in such an order mentioned above,mode switching can be performed safely. The controller 60 sets the stopvalve 125 corresponding to the indoor unit 2 that performed heatingoperation lastly after stopping the first pump 21 a at an extremelysmall opening area such that no heat medium flow therethrough to makethe flow path of the heat medium close (VT3). Then, processing at thetime of switching from cooling-main operation mode to cooling onlyoperation mode is terminated (VT4).

FIG. 18 is a flowchart showing the processing flow at the time ofswitching from the heating-main operation mode to the heating onlyoperation mode. Based on FIG. 18, descriptions will be given to theprocessing flow at the time of switching from the heating-main operationmode to the heating only operation mode. As explained in FIG. 15, at thetime of cooling-heating simultaneous operation in which coolingoperation and heating operation are mixed, that is, at the time ofswitching operation mode from the cooling-main operation mode or theheating-main operation mode, switching should be performed while payingattention to the order of ON/OFF of the compressor 10 and the pump 21.

The controller 60 starts processing at the time of switching from theheating-main operation mode to the heating only operation mode by theoperation instruction input from the remote controller (WT0). That is,the controller 60 switches the heat source side refrigerant flow at therefrigeration cycle side from the heating-main operation mode to theheating only operation mode (WT1). Then, the controller 60 stops thesecond pump 21 b at the cooling side (WT2). When the second pump 21 b isstopped prior to the switching of the operation mode, since the heatsource to evaporate the refrigerant disappears, low-pressure of therefrigerant decreases, possibly resulting in freezing of the heatmedium.

However, by switching operation modes in such an order mentioned above,mode switching can be performed safely. The controller 60 sets the stopvalve 125 corresponding to the indoor unit 2 that performed coolingoperation lastly after stopping the second pump 21 b at an extremelysmall opening area such that no heat medium flow therethrough to makethe flow path of the heat medium close (WT3). Then, processing at thetime of switching from heating-main operation mode to heating onlyoperation mode is terminated (WT4).

FIG. 19 is a flowchart showing the processing flow at the time ofswitching from cooling only operation mode to cooling-main operationmode. Based on FIG. 19, descriptions will be given to the processingflow at the time of switching from cooling only operation mode tocooling-main operation mode. At the time of the cooling-heatingsimultaneous operation in which cooling operation and heating operationare mixed, that is, at the time of switching operation mode tocooling-main operation mode or heating-main operation, switching shouldbe performed while paying attention to the order of ON/OFF of thecompressor 10 and the pump 21.

The controller 60 starts processing at the time of switching fromcooling only operation mode to cooling-main operation mode by theoperation instruction input from the remote controller (XT0). That is,the controller 60 opens the stop valve 125 corresponding to the indoorunit 2 that performs heating operation firstly (XT1). Then, thecontroller 60 starts the first pump 21 a at the heating side (XT2).Then, the controller 60 switches the operation mode to be stopped tocooling-main operation mode (LT3).

When the operation mode is switched prior to the start of the first pump21 a, high-pressure of the refrigerant increases and operationefficiency is deteriorated, possibly resulting in an abnormal stop.However, by switching operation modes in such an order mentioned above,mode switching can be performed safely. As shown in XT1, the stop valve125 corresponding to the indoor unit 2 having a heating load has to bemade open before starting the first pump 21 a and the heat medium flowpath has to be secured.

FIG. 20 is a flowchart showing the processing flow at the time ofswitching from the heating only operation mode to the heating-mainoperation mode. Based on FIG. 20, descriptions will be given to theprocessing flow at the time of switching from the heating only operationmode to the heating-main operation mode. At the time of cooling-heatingsimultaneous operation in which cooling operation and heating operationare mixed, that is, at the time of switching operation mode to thecooling-main operation mode or the heating-main operation, switchingshould be performed while paying attention to the order of ON/OFF of thecompressor 10 and the pump 21.

The controller 60 starts processing at the time of switching from theheating only operation mode to the heating-main operation mode by theoperation instruction input from the remote controller (YT0). That is,the controller 60 opens the stop valve 125 corresponding to the indoorunit 2 that performs cooling operation firstly (YT1). Then, thecontroller 60 starts the second pump 21 b at the cooling side (YT2).Then, the controller 60 switches the operation mode to be stopped to theheating-main operation mode (YT3).

When the operation mode is switched prior to the start of the secondpump 21 b, since there is no heat source to evaporate the refrigerant,low-pressure of the refrigerant decreases, possibly resulting infreezing of the heat medium. However, by performing switching in such anorder mentioned above, mode switching can be performed safely. As shownin YT1, the stop valve 125 corresponding to the indoor unit 2 having acooling load has to be made open before starting the second pump 21 band the heat medium flow path has to be secured.

As mentioned above, in the air-conditioning apparatus 200 according toEmbodiment 2, stop, start, or the switching of the operation mode of thecompressor 10 is performed when stop, start, or the switching of theoperation mode of the system is performed with the heat medium beingcirculated in the intermediate heat exchanger 15. Thereby, it ispossible to have stable operation and to prevent the refrigeration cycleoperation efficiency from being deteriorated such that high-pressure ofthe refrigerant becoming high or low, resulting in the improvement ofsystem efficiency and energy-saving.

That is, by performing stop control and start control, theair-conditioning apparatus 200 does no longer fall into poor efficiencyoperation conditions such that high-pressure of the refrigeration cycleincreases or low-pressure decreases, so that it is possible to improvethe operation efficiency of the entire system including start and stopand to achieve high energy-saving. When switching from the cooling-mainoperation mode to the heating-main operation mode or from theheating-main operation mode to the cooling-main operation mode, sincethe first pump 21 a and the second pump 21 b are in operation in bothoperation modes, they can be switched as they are.

In Embodiments 1 and 2, a case is explained where both the firsttemperature sensor 31 and the second temperature sensor 32 areinstalled. However, in order to control the first pump 21 a and thesecond pump 21 b, any one of the first temperature sensor 31 or thesecond temperature sensor 32 may be installed, and the other temperaturedetection means need not be installed.

In Embodiments 1 and 2, descriptions are given to a case where apseudo-azeotropic mixture refrigerant such as R410A and R404A, anon-azeotropic mixture refrigerant such as R407C, a refrigerant and itsmixture that is regarded to have a smaller global warming potential suchas CF₃CF═CH₂ including a double bond in the chemical formula, and anatural refrigerant such as carbon dioxide and propane are available asthe heat source side refrigerant, the refrigerant is not limitedthereto. In Embodiment 1, although an example in which the accumulator17 is provided in the heat source apparatus 1, the same operation andthe same effect can be expected without the same.

Generally, the heat source side heat exchanger 12 and the use side heatexchanger 26 are often provided with a fan and condensation andevaporation are promoted by an air blast, though, it is not limitedthereto. For example, a heat exchanger such as a panel heater utilizingradiation may be used for the use side heat exchanger 26, and awater-cooled type heat exchanger that transfers heat by water and anantifreezing liquid for the heat source side heat exchanger 12. A heatexchanger of any type may be used as long as having a structure capableof dissipating or absorbing heat.

An example is given to a case in which the flow path switching valve 22,the flow path switching valve 23, the stop valve 24, and the flow amountadjustment valve 25 are provided while corresponding with each of theeach use side heat exchanger 26, though it is not limited thereto. Forexample, to a single use side heat exchanger 26, two or more of them maybe connected. In such a case, the flow path switching valve 22, the flowpath switching valve 23, the stop valve 24, and the flow amountadjustment valve 25 connected with the same single use side heatexchanger 26 may be made to perform in the same way. Descriptions aregiven to a case where two intermediate heat exchangers 15 are provided,though, the number is not limited thereto. Three or more may be providedas long as configured to be able to cool and/or heat the heat medium.

A case is shown in which the flow amount adjustment valve 25, the thirdtemperature sensor 33, and the fourth temperature sensor 34 areinstalled inside the second relay unit 3 b, though, part of or all ofthem may be installed in the indoor unit 2. If they are installed in thesecond relay unit 3 b, since heat medium side valves and pumps or thelike are gathered in the same housing, there is an advantage thatmaintenance becomes easy. On the other hand, if they are installed inthe indoor unit 2, since they can be handled like a conventionaldirect-expansion expansion valve in the indoor unit, usability isimproved. Further, when they are installed in the vicinity of the useside heat exchanger 26, there are advantages that no impact is given bythe heat loss of the extended pipelines and the air-conditioning load inthe indoor unit 2 can be easily controlled.

1. An air-conditioning apparatus, comprising: at least one intermediateheat exchanger that exchanges heat between a refrigerant and a heatmedium such as water and an antifreezing liquid that is different fromsaid refrigerant; a refrigeration cycle with which a compressor, anoutdoor heat exchanger, at least one expansion valve, and a refrigerantside flow path of said intermediate heat exchanger are connected viapiping through which said refrigerant flows; a heat medium circulationcircuit with which a heat medium side flow path of said intermediateheat exchanger, a pump, and a use side heat exchanger are connected viapiping through which said heat medium flows; and a controller thatcontrols drive of said compressor and said pump, wherein said compressorand said outdoor heat exchanger are accommodated in a heat sourcedevice, said intermediate heat exchanger and said pump in a relay unit,and said use side heat exchanger in an indoor unit, respectively, andsaid controller performs at least one of operations to stop said pumpafter the stop of said compressor when stopping said compressor based onthermo-off due to decrease in air-conditioning load in said use sideheat exchanger or an operation stop instruction and to start saidcompressor after said pump is started when starting said compressorbased on the increase in air-conditioning load in said use side heatexchanger or operation start instructions while the compressor isstopped.
 2. The air-conditioning apparatus of claim 1, wherein a flowamount adjustment valve is provided that adjusts flow amount of saidheat medium to flow through said each use side heat exchanger at eitherinlet side or outlet side of the heat medium side flow path of said useside heat exchanger, and said controller stops said pump before stoppingall the heat medium flow paths by said flow amount adjustment valvecorresponding to the use side heat exchanger in operation lastly whensaid use side heat exchanger in operation lastly is stopped. 3.(canceled)
 4. The air-conditioning apparatus of claim 1, wherein a flowamount adjustment valve is provided that adjusts flow amount of saidheat medium to flow through said each use side heat exchanger at eitherinlet side or outlet side of the heat medium side flow path of said useside heat exchanger, and said controller starts said pump aftercontrolling said flow amount adjustment valve corresponding to said useside heat exchanger having the operation instruction or anair-conditioning load to make the heat medium flow path an open state.5. An air-conditioning apparatus, comprising: at least two intermediateheat exchangers that exchange heat between a refrigerant a heat mediumsuch as water and an antifreezing liquid that is different from saidrefrigerant; a refrigeration cycle with which a compressor, an outdoorheat exchanger, at least one expansion valve, and a refrigerant sideflow path of said intermediate heat exchanger are connected via pipingthrough which said refrigerant flows; a heat medium circulation circuitwith which a heat medium side flow path of said intermediate heatexchanger, at least two pumps, and a use side heat exchanger areconnected via piping through which said heat medium flows; and acontroller that controls drive of said compressor and said pump, whereinsaid compressor and said outdoor heat exchanger are accommodated in aheat source device, said intermediate heat exchanger and said pump in arelay unit, and said use side heat exchanger in an indoor unit,respectively, and said controller performs at least one of operations tostop said pump that does not correspond to an operation mode afterswitching operation mode when performing switching from cooling-heatingmixed operation mode that provides heating energy and cooling energywith said use side heat exchanger to heating only operation mode thatprovides only heating energy with said use side heat exchanger orcooling only operation mode that provides only cooling energy with saiduse side heat exchanger and to perform switching said operation modeafter starting said pump that has been stopped before switching theoperation mode when switching from heating only operation mode thatprovides only heating energy with said use side heat exchanger orcooling only operation mode that provides only cooling energy with saiduse side heat exchanger to cooling-heating mixed operation that providesheating energy and cooling energy with said use side heat exchanger. 6.The air-conditioning apparatus of claim 5, wherein a flow amountadjustment valve is provided that adjusts flow amount of said heatmedium to flow through said each use side heat exchanger at either inletside or outlet side of the heat medium side flow path of said use sideheat exchanger, and said controller, when switching operation mode andstopping said pump that does not correspond to the operation mode, stopssaid pump before controlling said flow amount adjustment valvecorresponding to the use side heat exchanger that does not correspond tothe operation mode to make all the heat medium flow paths close. 7.(canceled)
 8. The air-conditioning apparatus of claim 5, wherein a flowamount adjustment valve is provided that adjusts flow amount of saidheat medium to flow through said each use side heat exchanger at eitherinlet side or outlet side of the heat medium side flow path of said useside heat exchanger, and said controller, when making said pump startthat has been stopped before switching operation mode, makes said pumpstart after controlling said flow amount adjustment valve correspondingto the use side heat exchanger that corresponds to the operation mode tomake the heat medium flow path open.
 9. The air-conditioning apparatusof claim 2, wherein said flow amount adjustment valve is constituted bya two-way valve or a three-way valve.
 10. The air-conditioning apparatusof claim 4, wherein said flow amount adjustment valve is constituted bya two-way valve or a three-way valve.